• In addition to all the lightning and thunder, Humboldt County was struck by a 3.4 magnitude quake Saturday around 11:12 am. [NBC Bay Area]
• Amid the thunder, lightning, and ongoing conflict in Iran, residents in SF and the East Bay expressed concern Saturday night over a private 10-minute fireworks show displayed from a barge in the bay as part of an annual party for a local company. [SFGate]
• A warehouse worker in Southern California disgruntled with corporations allegedly started a fire at his workplace that caused $500 million in damages. [The Press-Enterprise]
• A small crowd of labor union and farmworker supporters braved the downpour Saturday to watch a scaled-down parade of dancers and performers at the 25th annual — newly labeled — Farmworkers Day Festivities in the Mission, despite all four of the event’s bands canceling due to the weather. [Chronicle]

• Cosplayers of all stripes converged on San Jose this weekend at Fandomcon Silicon Valley, a three-day convention celebrating multiple genres, including anime, comics, gaming, sci-fi, and popular culture. [KRON4]

Image: Leanne Maxwell/SFist

Over 5,000 lightning strikes were detected throughout California Wednesday, with 985 located in the Bay Area and Central Coast. Plus, two storms are forecasted this coming week, with an inch of rain expected in the North Bay and half an inch in SF.

As SFGate reports, a storm system originating in the subtropics is due to arrive in the Bay Area early Monday, while a second storm is expected to hit early Wednesday. National Weather Service (NWS)  meteorologist Nicole Sarment told SFGate that both storms are coming from the Gulf of Alaska and will be centered over the North Bay, which is expected to receive an inch of rain by the end of the week. San Francisco will likely get half an inch of rain, and the East Bay a quarter inch. The outlet reports that the rain is expected to dissipate by late Thursday with warmer weather arriving on Friday, just in time for the weekend.

Per SFGate, there’s only a 15% chance of lightning during the two incoming storms, unlike last Wednesday and Thursday when California skies were lit up by over 5,000 lightning events, as Bay Area News Group reports. There were 88 “cloud-to-ground” lightning strikes detected in the East Bay and South Bay between 7 pm Wednesday and 7 am Thursday, according to US Forest Service spokesperson Adrienne Freeman, as KRON4 reports.

NWS meteorologist Roger Gass told the Bay Area News Group that between late Tuesday night and early Thursday morning, 985 lightning strikes were spotted in the Bay Area and Central Coast region. Wildfires were a concern along the Central Coast, which was most impacted by the strikes — firefighters were monitoring 173 locations in San Mateo and Santa Cruz counties, per KRON4.

As the Bay Area readies for the incoming rain on Monday, NWS’s Sarment warns residents to be careful on the roads, explaining via SFGate that steady rain can bring oils to the surface, causing roadways to become very slick. “Make sure you’re driving slower with lights on,” she advised.

Image: Reddit

Along with the heat wave that’s expected Monday, Tropical Storm Mario, which briefly died then came back to life, could hit the Bay Area late Wednesday and into Thursday. The storm might produce some dry thunderstorms and a small amount of rain that's unlikely to hit the ground.

As SFist reported, San Francisco and the rest of the Bay Area are expecting 80–90 degree temperatures this week. In San Francisco, such high temperatures happen only a few days a year, when weather patterns briefly shift — calming the ocean breeze, flattening the marine layer, and reversing the wind so it blows offshore from the East Bay, per SFist.  

As SFGate reports, there’s a 15% chance that Tropical Storm Mario, which the Chronicle says is currently “steering a plume of moisture toward California,” will be adding more theatrics to the mix later in the week in the form of dry thunderstorms. Per the Chronicle, the storm died out last week and then started back up over the Pacific — just off the coast of Mexico, as the Instagram account, Rainy Day Weather, reports.

The Chronicle explains that a persistent layer of dry air near the surface will likely prevent rainfall from touching the ground. The lack of moisture could lead to lightning on Thursday and into Friday, posing wildfire risks.

Roger Gass, a Bay Area meteorologist for the National Weather Service, told SFGate his office is keeping an eye on potential fire weather concerns. “There’s a lot of variables in how these things pan out, and generally our confidence is low to moderate. But the impacts of dry lightning would be very bad for fire starts,” he said.

As a bit of consolation, the Chronicle notes that the Bay Area will be hit with mid-level cloud cover and slightly cooler temps leading up to Mario’s potential debut Wednesday night.

Image: Joe Parks/Flickr

Previously: Expect the Heat to Return to the Bay Area Monday and Tuesday

A series of wildfires that were sparked by lightning Tuesday afternoon in multiple locations across Calaveras and Tuolumne counties have prompted evacuations, and one fire damaged multiple homes in the town of Chinese Camp.

The group of 22 distict fires, now known as the TCU September Lightning Complex, began around 4 pm Tuesday, after seasonal, monsoon-driven thunderstorms swept through the area. Several fires quickly grew, one called the 2-2 Fire growing to 3,463 acres, and the largest, called the 6-5 Fire, growing to 6,473 acres overnight.

There are now nine separate fires of 15 acres or more, and the fires are 0% contained as of Wednesday. So far there have been no reports of injuries or deaths in the fires.

The 6-5 Fire swept into the Gold Rush-era town of Chinese Camp, with a population of 90 people, destroying multiple structures and mobile homes. According to the Associated Press, at least five homes were on fire there Tuesday night, but photos from the town show widespread destruction of structures.

According to Cal Fire, "The fire has exhibited active runs in critically dry tall grass, brush, and timber fuels. The terrain is challenging to access, requiring fire crews to hike in by foot to many remote locations." The number of structures destroyed has not been confirmed.

Chinese Camp in Tuolumne County, or Chinese Camp Town, took on that name in 1850, after originally being called Camp Washington. It was at that time home to thousands of Chinese prospectors who came to cash in on the California Gold Rush, after they were reportedly driven out of a nearby camp.

The TCU September Lightning Complex has now burned almost 19 square miles, or 11,977 acres as of Wednesday morning. The group of fires are 0% contained.

The 6-5 fire has prompted evacuation orders for the towns of Yosemite Junction and Keystone, and an evacuation warning is in place for an area just south of Jamestown.

The second-largest blaze, the 2-2 Fire, is burning on both sides of Highway 4, west of Telegraph City.

The 584-acre 2-7 Fire is burning in the hills north of Vallecito, south of La Honda Park, and east of Angels Camp, and it has prompted evacuation orders for parts of Vallecito north of Highway 4. Parts of the town south of the highway are under an evacuation warning. Part of the town of Murphys, to the north of the blaze, is also under an evacuation order as of Wednesday.

Some of the worst wildfires in recent California history have been sparked by dry lightning at this time of year, including the disastrous 2020 blazes the August Complex, the LNU Lightning Complex, the CZU Lightning Complex, and the SCU Lightning Complex, which, all told impacted six out of nine Bay Area counties, and a wide swath of Northern California.

The August Complex, which ultimately grew to over 1 million acres, surpassed the 2018 Mendocino Complex to become the largest wildfire complex in state history.

Two hikers were struck by lightning Thursday at the nearly 9,000-foot summit of Half Dome, and were confronted with the task of making it down after bouts with singed hair, charred clothing, and memory loss.

Perhaps the most challenging conquest in California hiking is reaching the summit of Yosemite National Park's Half Dome. The climax of the hike is effectively a straight-up vertical ascent of 400 feet, which hikers climb using cables that have been installed along the rocky slope. But even once you hit the top of the peak, the battle is only halfway over. Two hikers learned that the hard way Thursday, and the Chronicle has their harrowing tale of being struck by lightning on Half Dome, and their horrorshow test of endurance and resourcefulness to get to the bottom of the rock formation safely.

Hikers Jordan Dean and Josh Van Dyke recount that they reached the summit of Half Dome at about 12:30 p.m. last Thursday. They'd checked the weather before even attempting the hike, but saw a fast-moving storm approaching once they were on the summit. Two of their friends started their descent, but as rain and sleet conditions worsened, Dean and Van Dyke decided to wait it out at the top and hope for conditions to improve.

This may have been a wise call. Those that descended heard a woman scream, as she'd fallen down the north side of the mountain and hit a rock ledge. She would ultimately be rescued via helicopter. And meanwhile, one of the hikers' two friends also slipped and cut a knee, but both eventually made it down safely.

Meanwhile up at the top of the summit, Dean and Van Dyke took shelter in a rock cave as conditions worsened. And then lightning struck the cave.

“It felt like maybe a house voltage or like somebody punched me in the knee,” Dean told the Chronicle. The lightning struck through the rock to Dean’s knee, and to Van Dyke’s head. And then it happened again.

“The second time it struck was worse. It was way worse,” Dean added. “We saw the flashes, it was just like everywhere all at once.”

But they didn't even have it the worst. Another person in the cave with them was struck unconscious. “He hunched over, then his body went limp and he fell to the side,” Dean explained. “We were yelling for him to wake up and (one of my friends) was trying to shake him and then checked for a pulse.”  

They were able to revive the fellow hiker, but Van Dyke and the other hiker temporarily had no memory of where they were or how they got there. Van Dyke’s hair was singed, and the lightning had left a hole in his sock, likely where the bolt exited his body.

“It was scary not knowing if lightning was going to strike again or how bad,” Dean said. “There was nowhere to go and nothing we could do about it. That was terrifying.”

The weather passed, and the remaining hikers at the summit were able to descend. They encountered another group of women hiking down the cables, and one of them fell too. There were thankfully emergency personnel still on hand from the previous fall, and ultimately, no fatalities occurred on that horrifying day.

But there have been fatalities on Half Dome before. Seven people have fallen to there deaths from those cables, most recently 29-year-old Danielle Burnett of Lake Havasu City, Arizona in 2019. And in 1985, seven hikers were struck by lightning on the summit, two of whom died.

Related: Video: Skiing Duo Descends Treacherous, Spine-Tingling Shoulder of Yosemite's Half Dome [SFist]

Image: Diliff via Wikimedia Commons

Over the course of 24 hours beginning Friday evening, hundreds, if not thousands, of lightning strikes lit up the skies in and around the Central Coast, alarming residents and authorities.

The strikes, which appeared both on land and at sea, ignited fears of potential wildfires amid the region's dry late-summer conditions, according to KTVU. The National Weather Service issued a fire weather watch effective from 5 a.m. to 11 p.m. on Saturday, for areas situated above 2,500 feet in the Santa Lucia mountains, including the Los Padres National Forest, as well as the interior mountains of Monterey and San Benito counties.

While the fire weather watch was in effect, a red flag warning, signifying critical fire weather conditions, was also activated, as the Chronicle reported. However, this warning expired at noon on Saturday

The Santa Cruz Mountains were reportedly among the regions affected by the unexpected onslaught of showers and lightning strikes. Isolated strikes were also reported near San Jose.

The National Weather Service counted the total number of strikes exceeding 6,000, with both “cloud-to-cloud” and “ground strike” lightning, using one data source.

Meanwhile, another data source indicated a slightly lower figure, with over 700 strikes recorded.

On Saturday afternoon, the weather service said at least four small fires had been ignited in the region as a result of the lightning strikes, per KTVU.

Local authorities and firefighting agencies say they are closely monitoring the situation to respond to any new fire outbreaks in the wake of this unusual lightning event.

Feature image of a 2015 lightning storm in San Francisco via Flickr/Joe Parks under Creative Commons license.

Lightning strikes in San Francisco were caught on video people on Twitter on Tuesday, and bolts appears to strike the tip top of the Transamerica Pyramid — which is not unheard of — as well as Sutro Tower.

While the city was enduring another round of heavy rain and about three minutes of intense hail, during KRON4's noon broadcast, their camera feed catches a bolt of lighting that pretty surely struck the top of the Pyramid, though they're not confirming that to be the case. Even though you don't see any more of the bolt below the building's top, the station is just calling it lighting "over the Transamerica Pyramid."

KTVU's Kate Rooney, though, is calling it like she sees it.

And we have two other angles on it here, from SF residents who also had a view of the building on camera:

The building does not appear to be affected or damaged.

And we know that this has happened before — even though lightning is a relative rarity in SF. In January 2017, multiple Twitter users posted photos and video of lightning striking the tip of the Transamerica building.

A lightning bolt also struck Sutro Tower during the same hour of unstable weather, and this was also well documented on Twitter.

Local meteorologists assure us that all of this should pass by 2 p.m. — at least the very stormy part. More rain is likely this evening, and plenty more arrives tomorrow.

This post has been updated throughout to include the lightning strike at Sutro Tower.

Top image via quibblenibble/Twitter

We've been teased a few times this summer with threats of lightning that never materialized over Northern California. But with the added fire risk of this week's hot-hot weather, the threat of unstable air and dry lightning from the remnants of a hurricane is very rare in the coming days.

"I rarely share National Hurricane Center info when it comes to California weather, but it's quite relevant in this case: Former Hurricane #Kay will indirectly affect SoCal by Fri.," said UCLA climate scientist Daniel Swain on Twitter. Swain said he'd be making a more complete report later on Wednesday regarding the potential impacts of the dwindling hurricane off the Baja California coast. But he already spoke at a Twitter Spaces event Tuesday, per the Chronicle, and said it could create a "nightmare" scenario by this weekend or early next week.

"The concern would be dry or nearly dry lightning,” Swain said, per the Chronicle. "That would be kind of a nightmare in the context of the unprecedented heat wave we’re currently experiencing, and just before autumn wind season."

Fire meteorologist Nick Nostler also noted on Twitter that the National Weather Service Storm Prediction Center put out weather outlooks showing all five potential weather categories at once over far Northern California and the Northwest — meaning both scattered and isolated dry lightning predicted, and all three fire risk categories, Elevated, Critical, and Extreme.

Everyone still has fresh memories of the August 2020 lightning complex fires that upended life in multiple parts of the Bay Area, with firefighters battling enormous blazes in three areas and on multiple fronts for weeks.

On the other side of the prediction spectrum, we have Cal Fire CZU Unit Chief Nate Armstrong telling the Chronicle, "I keep seeing the forecast change every couple hours; are we going to get some moisture or not, are we going to get some dry lightning or not? It seems too early to tell."

We're getting some of that rare summer precipitation in San Francisco and elsewhere around NorCal, thanks to monsoonal moisture drifting our way from the desert Southwest.

You may have woken up to a wet front porch or back deck on Monday, and smatterings of rain continue to fall around the city.

The National Weather Service warned of possible lightning and scattered showers on Sunday, but so far very little lightning has been detected. Radar picked up a lightning strike in Monterey County Monday morning, as the isolated pockets of moisture continue to move through the region. A few hours earlier, the weather service spotted some lightning off the Marin County coast.

Sarah McCorkle, a forecaster with the weather service, tells SFGate that the chance of thunder and lightning in our area will drop off significantly after 2 p.m. Monday.

"On our radar right now I see some rain moving into our area in the next few hours. There's about a 15% chance we could get a lightning strike or two," McCorkle said.

The Weather Channel predicted a 50% chance of showers in SF around noon.

Overnight rainfall was extremely minimal, though parts of the North Bay saw a couple one-hundredths of an inch hit the ground.

The last bout of monsoon moisture to come our way was from some early-season rain in the Southwest in late June. We're now more in the thick of the season, and we should brace for more forecasts like this.

Otherwise, the weather this week should be pretty Fogust-typical, with the sun coming out by Wednesday and warming things up a bit with a forecast high of 67 on Thursday in San Francisco.

Photo: Thibaut Thiberghein

Moonsoonal moisture is on its way over California this week, which will bring the possibility of some light rain, and also, more ominously, lightning in some already fire-prone areas.

Everyone here will recall the apocalyptic summer of 2020, when lightning-sparked wildfires consumed huge swaths of our region — all of which began during a mid-August spate of monsoonal moisture coming from the south. The weekend saw some early monsoon-season rain in Arizona — which the whole Southwest desperately needs, as their drought conditions are even worse than ours in some spots. But that moisture moving up over the California coast brings the potential for dry thunderstorms, and only a little bit of potential for actual precipitation for the Bay Area.

The National Weather Service is warning of possible lightning-ignited fires between Wednesday and Thursday, and they say that the Bay Area and Central Coast are the areas of greatest concern.

Periods of monsoonal moisture came our way in August and September of 2021 without any major lightning incidents, but the memories of two years ago are still pretty fresh.

And it seems like not that long ago, lightning was an exceedingly rare occurrence around the Bay, but starting around 2017 we've seen a few more summertime lightning storms, including this one in September 2017 where a photographer captured lightning striking Salesforce Tower.

Meteorologist Daniel Swain says the wetter areas for this weather system are likely to be in the Southern California mountains, and dry thunderstorms are likelier in the Central Valley and closer to us.

Sarah McCorkle, a National Weather Service meteorologist, tells the Chronicle, "The Bay Area itself won’t get a whole lot from this," but parts of the East Bay and North Bay could see a bit of moisture starting late Wednesday. And lightning tends to be fairly difficult to predict.

Meanwhile, San Francisco is having a heatwave day, with temperatures expected to hit highs in the 80s today. But this is forecast to be the last super warm day in the city this week, with the rest of this week seeing part sun and average temps around 65 degrees.

Photo: Johannes Plenio

Some more welcome rain is coming to the Bay Area on Saturday, though rainfall totals will be pretty modest. And you may see some lightning.

A weak weather system moves in to our region Saturday morning, and will bring rain to San Francisco and the whole Bay Area into Saturday afternoon or evening.

The National Weather Service is calling it a quarter of an inch maximum in most places, though ABC 7 suggests some places might see up to half of an inch of rain. Also, expect some gusty winds, with gusts potentially topping 40 mph at the coast.

ABC 7 rates this a "1" on its storm scale, and it doesn't sound like the rain will stick around for long.

Things will stay pretty chilly into Sunday, when there's a sunny day predicted with a high of 59. And then it warms up again, with highs in the high 60s and maybe even up to 70 midweek.

And let's hope that this thunder and lightning is kept to a minimum, given the minimal rain this storm is bringing, and the already dry and crispy conditions developing around the region. We don't need fire season starting just yet.

Photo: Felix Mittermeier

This week's lightning scare became an actual lightning storm on Thursday night, and around 110 cloud-to-ground lightning strikes were recorded across the Bay Area during a time of extreme fire danger. The National Weather Service said there were "Too many cloud to cloud flashes to count."

Two small fires were caused by the strikes and quickly extinguished, and at least for now, fears of a repeat of last summer's devastating conglomeration of lightning complex fires are abating.

As of 9 a.m. Friday, the National Weather Service called off the Red Flag warning for the area, which had been set to expire at 11 a.m. The reason was that the unstable air and thunderstorms had all moved east of our region.

There were eight confirmed lighting strikes in Sonoma County as of 9:45 p.m. Thursday, and one strike near the Napa border sparked a small fire that was extinguished. Another lightning-caused fire in Mendocino County, near the Sonoma border and the town of Cloverdale, had grown to eight acres as of Friday morning, as the Press Democrat reports. The fire was in a very hard-t0-access, remote area, and it was 0% contained. It has been named the Rock Fire.

One lightning strike was within the burn scar of last fall's Glass Fire, east of Santa Rosa. As of Friday morning, the Santa Rosa Fire Department reported no significant blazes in the city.

Local photographer Kent Porter captured a lightning strike behind Mount Saint Helena, and said these were the "brightest bolts of lightning" he'd ever photographed.

The storms produced a small amount of rain, and about one-tenth of an inch was recorded in Kenwood.

As the Chronicle reports, there was one small fire in the Oakland hills around 8 p.m. that only grew to 100 square feet before being contained.

Fears remain that these weather systems would exacerbate the existing wildfires in the Sierra, but it's not yet clear what impact they will have. The Dixie Fire now stands at 59% contained, and the Caldor Fire is 53% contained as of Friday morning.

Update: Winds from the storms whipped up the northern edge of the Dixie Fire, which made a 13-mile run that was six miles wide, near the Shasta County town of Old Station.

Photo via Santa Rosa Fire Department

Much of Northern California is in for another lightning scare this week, amid a summer of unusually frequent brushes with tropical moisture that creates the potential for lightning.

There is a higher likelihood of dry lightning late Thursday into Friday morning than in the previous lightning scares this summer, as meteorologist Daniel Swain of Weather West explains. The conditions are ripe for the kind of atmospheric instability that creates lightning, and there is only a slight chance of moisture, with less than a tenth of an inch of rain possible in some places.

"The models had looked pretty ho-hum regarding this week’s potential event until yesterday, but today’s runs are trending in a direction of substantially increased risk," Swain wrote on Tuesday. "In fact, today’s latest couple of model cycles are starting to depict what appears to be the classic set-up for an autumn lightning event in northern California."

And on Wednesday, Swain confirmed on Twitter that the model continues to show this strong potential for lightning.

"My thoughts from yesterday haven't changed much--in fact, confidence in some level of dry lightning has increased," he says, adding that the highest potential will be north of I-80. He adds that the lightning risk for the North Bay will be highest Thursday afternoon and evening, and the risk will shift more to the East Bay on Friday morning.

A Fire Weather Watch has officially been called for the North Bay from Thursday through 11 1.m. Friday.

Swain still cautions that this could end up being just another scare, like the last two in July and August, but he says there is more likelihood for this lightning event to materialize.

"There is always 'bust potential' with dry lightning events in CA, and the two possible events earlier this summer did just that: they largely failed to materialize," Swain writes. "But this one has somewhat lower 'bust potential' than the earlier two, as in this case the weak low pressure system and mesoscale lift will provide a clearer focal point for triggering some elevated convection compared to the unstable but forcing-less non-events earlier this year."

And, he adds, conditions are pointing to "a dry environment favoring strong downdraft winds with any thunderstorms that develop — things could get dicey indeed on existing firelines."

The last thing anyone needs a repeat of the lightning event that happened on August 17 and 18 last year, which sparked wildfire complexes that scorched thousands of square miles across three zones of the Bay Area, destroying homes, killing people, and choking the region with smoke for well over a month.

As Jeff Lorber, a National Weather Service meteorologist, tells the Chronicle today, "Any lightning strikes pose significant hazards to our area because of very dry fuels, especially with the recent heat that we’ve been having and the very dry air mass that’s settled into place."

Photo: Leon Contreras

An area of high pressure over the southwestern U.S. will be sending warmer temperatures our way in the next few days, particularly in the inland parts of the Bay Area. And meteorologists are closely monitoring the situation as some more monsoonal moisture moves our way.

This whole thing with monsoonal moisture in the summer, coming from the southwest, seems to be a new thing the media discovered this year — given the devastating impact of one lightning storm on our region last August, caused by some similar moisture. But this happens seasonally in many parts of the world, and the National Weather Service says this has been a particularly "robust" monsoon season for the Desert Southwest, which is why there have been seemingly biweekly scares about dry lightning here around the Bay for the last couple of months. (We also saw some of this in August of 2017, in addition to last August.)

But it takes unstable air combining with that moisture to create thunderstorms, and so far that doesn't appear to be happening this week, but it still might, as National Weather Service Bay Area forecaster David King say in the briefing seen below.

"As of right now, the instability needed to create a storm [is] staying a little bit further separated from the moisture," King says. "So there's no fire [warnings] issued currently. But we are watching this very closely."

King says we will see the moisture move into the Bay Area by Thursday morning in the form of high clouds, and temperatures will begin to rise and reach the 90s in some locations — though probably still just the 70s in SF.

As the NWS explained on Twitter yesterday, "Thankfully, the setup for this upcoming monsoonal moisture return does not remotely come close to last year's setup in terms of moisture content, instability, and source of lift. Nonetheless, all it takes is 1 lightning strike over a dry fuel environment to trigger a fire start."

You can see the mass of moisture in the GIF below moving over Las Vegas, where it already is causing a cluster of storms.

The NWS says that we're very likely not to see much of this moisture head into our region at all.

"While most of this moisture won't make it here, some of it will get picked up by southerly winds aloft and [get] lodged here," the weather service says on Twitter.

Fingers crossed we just have a brief heatwave and no storms!!

Below is an explainer about how lighting happens, from the NWS Los Angeles bureau.

Previously: Monsoonal Moisture Brings Small Chance of Lightning and Rain to Bay Area