Buckle up and turn on those fans, kids, because the hot weather is just going to stick around through the end of the week.

Heatwaves aren't too common in March in San Francisco. And it's especially strange to have a stretch of hot weather, in March or any other time of the year, that goes on for a week or more.

It's been pretty warm in the city since Thursday, and the forecast has this hot spell lasting at least through Friday of this week. If the high temperatures get to 84 degrees or above each day this week, the Chronicle notes that this would mark the longest stretch of that kind of hot weather in any month in SF since the city's main weather station moved to the Mission District in 2007.

Also, the forecast highs in the city, starting today, are expected to be in the top ten hottest days ever recorded in March in San Francisco. If the high hits 88 degrees on Tuesday, as it is forecast to, that would break the record for being the hottest March day ever recorded here.

So, what gives? Why this "marathon" heat wave, as the meteorologists are calling it, in the middle of March? It's a so-called heat dome, or an area of strong high pressure sitting high in the atmosphere. Per the New York Times, "Air descends to the ground and heats up, and the sinking air acts like a lid, trapping warmer air close to the ground."

This heat dome is impacting much of the West and desert Southwest, and records are expected to be broken in Los Angeles and Phoenix as well. The record for Phoenix's first 100-degree day of the year was set in 1988, and it was on March 26, and that city is expected to see a 100-degree day a full week earlier than that this week.

The National Weather Service is also warning that people should be careful doing anything outside, because our bodies are not as acclimated to warm temperatures as they would be later in the year.

"This is our first major heatwave of the year and it is going to be a marathon," says the National Weather Service. "Given the long duration of this heat event, susceptibility to heat related illnesses will increase throughout the week. If you are going to be outside for prolonged periods of time make sure you are drinking plenty of water and allowing time to rest in the shade."

According to the National Weather Service, the high in downtown SF today is expected to be 84, tomorrow is expected to hit 88, and Wednesday is expected to hit 87. (The Times has lower numbers for SF, with 83, 87, and 85.)

Top image: A photo from an SF heatwave in 2011. Photo by Justin Sullivan/Getty Images