Excessive heat in Northern California lingering through weekend; gradual relief in sight

An incessant and dangerous heat wave blistering Northern California peaked Sunday with another round of record-breaking temperatures in the Bay Area and Sacramento Valley before gradual cooling begins.

The National Weather Service said an Excessive Heat Warning was still in effect through 11 p.m. Sunday for most of the Bay Area including San Francisco. Coastal areas are under a Heat Advisory until 11 p.m Sunday. There is a major to extreme heat risk for mountain areas and nearby passes, with heat-related illnesses including heat stroke being a risk to everyone, the Weather Service said.

San Rafael hit the highest temps in the Bay Area on Sunday, at 107 degrees. The closest temperature match there was when the city was 95 degrees back in 2023. Also in Marin, the town of Kentfield hit 102, beating out the previous high of 97 in 1930. 

In Sonoma County, Santa Rosa reached 102 degrees, matching the same temps for this day in 1930. 

In Napa County, highs at Napa State Hospital topped 102, also beating out the heatwave of 1930 when it was measured at 96 degrees. 

Downtown San Francisco also beat its previous record of 94 in 1992, by reaching 97 degrees. At the airport it was 98 degrees, beating 2023's high of 92. 

In the South Bay, Redwood City reached 102 degrees, 3 degrees higher than its record of 99 in 1987. San Jose hit 103, beating out 2023's 95-degree record. And the Salinas airport clocked a high of 98 degrees, matching 2023's high. 

The NWS notes that all these numbers are preliminary and official temps will be released from the National Centers for Environmental Information.

The heat wave will last longer in the Sacramento area, where a Heat Advisory was in effect until 11 p.m. on Monday, and the Weather Service said there will continue to be widespread moderate to major heat risk across the Valley, Delta, and foothills which could impact outdoor activities.

Potential relief is in sight as a marine surge has the potential to impact coastal areas and limit the upper end of the high temperatures, the Weather Service said. The cooling surge along the San Francisco Peninsula could reach the city of San Francisco, bringing the potential of a 25-degree temperature difference from one end of the city to another, the service said.

Temperatures in the Bay Area are expected to begin a gradual downward trend starting Monday with a steady decline into mid- week. 

In the Sacramento Valley, temperatures are forecast to remain in the upper 90s to around 102 on Monday, with the hottest temperatures once again in the Delta, southern Sacramento and Northern San Joaquin Valleys. Relief from the heat will begin Tuesday with a gradual cooldown accompanied by possible chances of showers north of Interstate Highway 80 and higher elevations late this week.

In:
• Heat Wave