Welcomed cooling trend heads to Bay

“It was a widespread heat event, but cooler this week. The heat is now done and we’re going back to more normal temperatures. For some people, it’s going to feel chilly; we’re dropping almost 30 degrees,” Bell said Monday afternoon.

A little chill is probably a welcomed reprieve from the weekend’s blistering heat and absent winds.

September and October tend to be some of the region’s warmer months but usually maintain a cooler marine layer that carry in ocean wind. That natural air conditioner was essentially nonexistent this last weekend, Bell said.

That led to extreme heat and some record-setting temperatures. In San Mateo County, San Francisco International Airport hit an all-time high of 104 degrees. To the north, San Francisco shattered records with temperatures hitting 106 degrees Friday, three degrees higher than ever recorded.

“That’s substantial considering the records go back to the 1800s,” Bell said.

By Saturday evening, six all-time Bay Area records were broken.

Redwood City experienced a punishing 108 degrees Friday and Saturday, which were the fourth warmest days on record. The hottest ever recorded was 110 degrees in 1972. For comparison, this time of year is usually marked by a high of about 81 degrees, Bell said. By Sunday, temperatures had cooled to 92 degrees and were expected to drop.

Portions of Pacifica also topped the charts with inland temperatures of 103 degrees, slightly higher than the prior 102-degree record, although Bell noted those statistics only date back to 1983.

Still, “it was some of the warmest, if not the warmest, weather for that area in the last 30 years,” he said.

Temperatures are typically cooler closer to the ocean, and the typically foggy Half Moon Bay welcomed thousands of visitors to its beaches. Temperatures in the coastal town hit a high of 90 degrees Friday and Saturday, before dropping back down to the 70s and 60s Sunday and Monday, according to the Weather Service.

In the Pacific Ocean off the coast of San Francisco, a weather station at the Farallon Islands marked an all-time high of 89 degrees, which is considerable when comparing the average 50s and 60s it normally experiences, Bell said.

The warm weather was felt throughout the region with Santa Cruz hitting 107 degrees, Monterey and Oakland about 101 degrees, and Mountain View tying its all-time record at 106 degrees. Reports from Boulder Creek in the mountains near northern Santa Cruz County hit 115 degrees, as did areas to the south like Gilroy and Morgan Hill, Bell said.

“Those are very big numbers, and when you think about Las Vegas, its all-time high is 117. So for places around here to be that high is very significant,” Bell said.

Bell clarified the extreme heat wave was unrelated to larger national events such as Hurricane Harvey. But the warm air mass compressing the Earth’s surface was expected to shift east of the Bay Area. Moisture left over from Tropical Storm Lidia that hit Baja was pointed to as the source for Monday night’s chances of showers and thunderstorms in the South Bay, according to the Weather Service.

The cooler marine layer is returning and Bell predicted the end — at least in the foreseeable future — of the extreme heat.

“There was no cooling from the ocean. That’s why even near the coast we saw very widespread hot conditions,” Bell said, adding smoke will also start to clear and by Tuesday “conditions will begin to improve and be a lot better as the week goes on.”

samantha@smdailyjournal.com

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Twitter: @samantha_weigel