The possibility of lightning has led to Red Flag Warnings Monday and Tuesday in some of California’s northernmost counties, but the low-pressure system that’s bringing them will mostly just bring more fog to San Francisco.

It’s only Monday morning, but needless to say, everyone's already just thinking about the big three-day holiday weekend ahead. And we're starting to get some reliable weather forecasting on what this week — and more importantly, this weekend — will look like in the Bay Area and beyond.

The Chronicle has the surprising report that thunderstorms are a possibility in parts of Northern California this week, particularly early in the week. You would not need to worry about these thunderstorms unless you’re driving as far north as Eureka, but both wet and dry thunderstorms are in the forecast for Shasta, Siskiyou, and Trinity counties, and across the northern Sierra Mountains. But that also means wildfire risk, and those areas are under red flag warnings today and tomorrow.

The same low-pressure system that could bring lightning up north will also bring the Bay Area a rather cool and foggy week. KGO’s seven-day AccuWeather forecast has San Francisco with temperatures in the 60s and 70s this week, with temperatures in the East Bay about ten degrees warmer.

Unfortunately, Friday, July 4 is currently expected to be the chilliest and foggiest day of the week. It’s a far cry from last year’s July 4 when SF temperatures were in the 80s, while the East Bay and North Bay saw some temperatures above 100 degrees. This year’s July 4 in SF is expected to see SF temperatures in the low 60s, with much of the day just in the upper 50s. Parts of the East Bay may only see temperatures as high as 80 degrees.

In other words, for San Francisco at least, it will likely be another July 4 where the fog will inhibit your view of the fireworks.

Related: This Is What Thursday's Fireworks Looked Like In SF [SFist]

Image: Lightning bolt in the dark night sky in close up. (Getty Images)