S.F. Bay Area heat wave will be a ‘marathon,’ weather service warns. Here are the details

The National Weather Service forecasts hazardous heat across much of California, with “many monthly March records” likely from March 17 to 21.

“The National Weather Service forecasts hazardous heat across much of California, with “many monthly March records” likely from March 17 to 21”

San Francisco Chronicle

Temperatures are forecast to be 20 to 30 degrees above normal in the Bay Area.

San Francisco Chronicle

Record-shattering March heat is forecast across the Bay Area this week as temperatures are anticipated to surge into the 90s, as much as 30 degrees above normal for this time of year.

It won’t be a short-lived spike in temperatures: “It is going to be a marathon,” the National Weather Service said.

The weather service on Saturday issued a heat advisorygoing into effect at 10 a.m. Monday and continuing until 8 p.m. Friday for the entire Bay Area, excluding Solano County.

San Francisco’s high temperature is forecast to be 84 degrees or higher Monday through Friday, according to the weather service.

San Francisco Chronicle

It would tie the longest such stretch in any month since the city’s official weather station moved to the Mission District in 2007.

Tuesday and Friday are predicted to be the hottest days, at 88 degrees, which would shatter San Francisco’s all-time March temperature record of 87 degrees, set in 2005.

“The National Weather Service forecasts hazardous heat across much of California, with “many monthly March records” likely from March 17 to 21”

San Francisco Chronicle

Temperature records began in the city in 1875.

It’ll be even hotter elsewhere.

San Jose is expected to flirt with 95 degrees Tuesday through Friday.

A 95-degree reading would break the old March record by 6 degrees, tying San Jose’s biggest margin to beat a previous monthly temperature record in more than a century.

“Near Oakland you could be cracking 90 … near 100 if you’re going to Pinnacles (National Park),” said Karleisa Rogacheski, a meteorologist at the weather service office in Monterey.

There’s a low-end chance of triple-digit heat in the Santa Cruz Mountains, interior East Bay valleys and the Oakland and Berkeley hills.

Long March nights will limit the duration of extreme daytime heat, but limited overnight relief is expected.

Most areas will remain in the 60s by Tuesday night, with hills areas above 500 feet possibly remaining in the 70s, including Twin Peaks and the Oakland and Berkeley hills.

San Francisco Chronicle

These are known asthermal belts.

Amoderate risk of heat-related impactsis expected for nearly the entire Bay Area, probably affecting sensitive populations such as the elderly or people with underlying health conditions.

The weather service recommends people seek adequate cooling and remain properly hydrated.

“It’s very unusual for this time of year to have these temperatures,” Rogacheski said.

“It’s not going to be what our bodies are used to.”

Above-normal temperatures are forecast to continue through next weekend, but the stubborn area of high pressure may finally begin to break.

“It really doesn’t start moving until Saturday night. … We should see some relief Sunday,” Rogacheski said.

“By Monday we start to see some more zonal flow. That is a good indicator across all the models that we won’t have those unusually high temperatures.”

Temperatures this high would have beennearly impossible in past decades.

Anthropogenic greenhouse gas emissions are trapping heat in the atmosphere and resulting in more extreme heat records and less frequent instances of extreme cold.