How long will Bay Area heat wave last?

( KRON ) — An extended heat wave that has already brought record-breaking temperatures to several parts of the Bay Area could last for several more days, or possibly even weeks. The heat wave, which the National Weather Service has called “historic,” “lethal” and “exceptionally dangerous,” could stretch on into the middle of July, according to KRON4 Meteorologist Lawrence Karnow.

“This is going to be an extended heat wave making it unusually dangerous for the elderly and children, or those most affected by heat,” Karnow said. “I expect Wednesday to be hotter than Tuesday, with highs soaring to 108 to 112 inland, 90s and 100s around the Bay, and 70s at the coast.”

4th of July forecast

The 4th of July holiday might bring some respite from the heat, but already, some Bay Area cities are canceling holiday events due to the extreme heat in the forecast.

“I think we will see some cooling on the 4th, but high temperatures inland will still be in the 98 to 104 range,” said Karnow. “In fact, I have a 100-degree temperatures plus forecast for the valleys through next week.”

Rolling blackouts possible

We’re just two days in and the current heat event has already led to power outages in the East Bay and other parts of the Bay Area.

“I suspect the long duration will put substantial pressure on the power grid,” Karnow said. “Losing power could be extremely dangerous for those most susceptible to the heat. Looking at the California ISO energy forecast for Wednesday, it is close to its limit.”

With PG&E having already warned of potential Public Safety Power Shutoffs (PSPS) , Karnow believes there could be more such events ahead.

“I think rolling blackouts are very possible,” he said. “Something for us to watch going forward.”

No cooldown in sight

An excessive heat warning and heat advisory for the greater Bay Area has now been extended until 11 p.m. on Wednesday, July 10, the NWS said. The city and county of San Francisco will remain under a heat advisory until 7 p.m. on Thursday, July 4.

Unlike previous heat events this year, nighttime is expected to bring little respite to the heat this week.

“Nighttime temperatures in the valleys will stay high in the 70s, which means the body doesn’t have a chance to cool down and recover before the next hot day,” Karnow said.

The high temps, offshore winds, and dry conditions have already seen a number of fires break out in the Bay Area . Fire danger could persist through the weekend.

“Of course, offshore winds will decrease the amount of moisture in the air and lead to high fire danger through the holiday,” Karnow said. “Heat advisories and warnings are up until next Tuesday and may need to be extended.”

So how long will the heat last? According to Karnow, that might be a question of weeks, rather than days.

“Right now, I don’t see a significant end to the hot weather pattern through the middle of July,” Karnow said. “I hope I’m wrong.”

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