Heat drains power, knocks out BART

Pacific Ocean breeze were no strangers to the heat. In Half Moon Bay, the highest temperature ever recorded for June 10 — 75 degrees in 1941 — was toast as thermometers measured 89 degrees on Monday afternoon, said Anna Schneider, a National Weather Service meteorologist.

“We haven’t seen that surge of clouds, it’ll probably hold off for another day,” Schneider said.

More than 26,000 residents and businesses throughout the Bay Area lost their power as the heat intensified.

According to numbers released by Pacific Gas & Electric Co., 14,642 customers in the East Bay suffered outages, while South Bay customers reported 5,067. Blackouts hit 4,281 people in San Francisco, 1,824 on the Peninsula and 634 in the North Bay.

Among the areas that lost power was Fisherman’s Wharf in San Francisco.

The heat also warped tracks on BART Monday afternoon, and crews worked to cool down equipment as delays reverberated throughout the system, according to the transit agency.

Cooler weather may finally abound on Tuesday, with temperatures up to 10 degrees cooler in the forecast.

Weather officials are likely to issue another heat advisory for parts of the inner East Bay, where triple-digit heat is expected for at least one more day.

A shallow marine layer will likely return by Wednesday to bring widespread cooling and return thermometers to normal levels.

“Drink plenty of fluids, stay in an air-conditioned room if possible, or stay in the shade and out of the sun during peak heating hours,” said Scott Rowe, a National Weather Service meteorologist. “Check on your relatives and neighbors.”

The Bay Area Air Quality Management District issued a spare-the-air alert for Tuesday, with air quality measuring as unhealthy for sensitive groups in the eastern part of the region.

Smoke from the Sand Fire in Yolo County, along with other small brush fires burning in Marin and Contra Costa counties could continue to impact air quality. Forecasters said winds could push a thin stream of smoke from the Sand Fire over the North Bay as the blaze continues to burn.

Chronicle Staff Writer Rachel Swan contributed to this report.

Liz Hafalia / The Chronicle Claudia Aguilar cools off her daughter, Kylie Vanessa Aguilar, at Del Valle Regional Park near Livermore. Monday was the hottest day of the year in the Bay Area.