"Millions of people are either under an excessive heat watch or an excessive heat warning for hot temperatures on Saturday, Sunday and Monday," said Tuma.
There's a call for voluntary electricity conservation, beginning Saturday and extending through Monday, from 3 p.m. to 9 p.m.
"Power grid operator predicts high heat, energy demand this holiday weekend," said the California Independent System Operator (ISO) in a statement.
RELATED: What is a Flex Alert?
The Bay Area's excessive heat watch goes from Saturday at 11 a.m. to Monday at 9 p.m.
"We are tracking temperatures over 100 degrees at times," said Tuma.
Forecast highs for Saturday include 103 in Fairfield and 102 in Livermore. Concord and Antioch are also expected to reach 100.
"Sunday is forecast to be the hottest day over the holiday weekend," said Tuma.
Expect hot weather in the North Bay, South Bay and East Bay.
Fairfield could reach a scorching 111-degrees on Sunday, 109 in Antioch and Livermore, 108 in Concord, 105 in Napa, 101 in Santa Rosa, 98 in Petaluma, 97 in San Jose, 83 in Sausalito and 75 in San Francisco.
"We are going to track the sea breeze very closely because any minor change in it could mean San Francisco warms up into the 80s. I think 75 might be a little low for the Sunday forecast, we may have to bump that up to into the low 80s," added Tuma.
Inland neighborhoods will continue to sizzle over 100 degrees on Monday.
"Tips to beat the heat include include saying hydrated with water, taking frequent breaks in the shade, do not leave people or pets inside cars. If you are outside apply sunscreen regularly and also wear lose, lightweight clothing," said Tuma.
The California #ISO is issuing a statewide #FlexAlert, a call for voluntary electricity conservation, beginning Saturday and extending through Monday, from 3 p.m. to 9 p.m., due to excessive heat in #CAwx. https://t.co/Ad9ymjCtwX pic.twitter.com/8MIT2Esu3D— Flex Alert (@flexalert) September 3, 2020
Dangerous heat will move into the Bay Area this weekend with temperatures reaching near 110 degrees Inland. https://t.co/KwokRgrpdn— LiveDoppler7 (@LiveDoppler7) September 3, 2020
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