The mercury has also been unseasonably high elsewhere in the West this week, with Arizona and Nevada already seeing midsummer heat.

"I'm hot, muggy, sweaty. The sun's beating me up," said Danny Drum, a construction worker pushing a wheelbarrow in Las Vegas, where the temperature Tuesday afternoon was 105, one degree short of the record for the day.

Phoenix headed toward a 110-degree day Tuesday, its second straight in record territory, but that was almost cool compared to other places in Arizona - it was a record 117 in Lake Havasu City and 116 in Bullhead City.

"Your brain goes numb," said Brad Meyer, a roofer in Lake Havasu.

Even San Francisco, usually foggy and cool well into spring and early summer, saw record hot weather this week, topping 93 degrees Sunday. That shattered the state's record for the day - 86 degrees in 1886.

The heat wave struck while some power plants were down for pre-summer maintenance, said Patrick Dorinson, spokesman for the Independent System Operator, which oversees the state's power grid.

Widespread air conditioner use prompted utility regulators to declare an emergency Monday. Some businesses shut down in times of unusually high demand in exchange for discounts on their power bills.

But by Tuesday, the power grid was back to normal, and easing temperatures forecast for the rest of the week should allow maintenance to continue.

When the temperature topped 100 in Sacramento this week, restaurant manager Lu Mohatt decided to have a sale - 10 percent off for customers who picked up their own orders.

"I hate to send my runners out in the heat," she said. "I'm always after them to drink more water and stay out of the heat when it's like this."

With temperatures still in the upper 90s Tuesday, the cafe's sidewalk tables sat empty as customers sought air conditioned spots inside.

Because of the heat, the Squaw Valley ski resort near Lake Tahoe, which expected to stay open Memorial Day weekend, may have to close some runs, spokeswoman Katja Dahl said.

But the Mammoth Mountain ski resort in central California expects to stay open into June, said spokeswoman Joani Saari.

"Last week we had four inches of new snow," she said. "It's been weird."

AP-ES-05-23-00 2009EDT