A rare heat wave hitting the San Francisco Bay Area is expected to peak later than initially forecast, with increased temperatures anticipated on Wednesday. On Tuesday, Concord in the East Bay hit 102 degrees, and meteorologists expect it to soar to 107 degrees on Wednesday. Rachel Kennedy, a forecaster for the regional weather service, noted that the heat peak has shifted to today.
Inland areas may experience temperatures reaching as high as 110 degrees, while coastal areas could see highs up to 95 degrees. This heat is being driven by a high-pressure ridge over the Pacific that will persist in California for an extended period. The excessive heat warning that was set to expire on Wednesday evening has now been extended to 11 p.m. Thursday, indicating that the heat will remain significant into the weekend.
The overnight temperatures have been unusually high; for example, a weather station in the Berkeley Hills recorded a staggering 90 degrees at 7 a.m. on Wednesday, which is estimated to be 30 to 35 degrees above normal. Many homes in this region lack air conditioning, thus worsening the heat conditions.
Kennedy pointed out that major heat risks are impacting the East Bay and South Bay areas, particularly in elevated regions. While autumn is typically thought of as a season for cooler weather, it often sees some of the Bay Area’s most intense heat waves. Joe Merchant, another forecaster, explained that temperatures can be 20 to 30 degrees above normal during this time, especially due to the absence of the marine layer, which usually provides natural cooling along the coast.
This week’s offshore winds, referred to as Diablo winds, have disrupted the marine layer, causing coastal areas to experience significantly higher temperatures than usual. Downtown San Francisco recorded its hottest day of the year on Tuesday with a high of 93 degrees, and 90 degrees are expected again on Wednesday.
Inland regions faced extreme heat, with several cities setting new temperature records. San Rafael recorded a high of 105 degrees and Kentfield hit 100, both breaking prior daily records. San Jose also reached a record of 100 degrees. More record highs are anticipated on Wednesday, with Kentfield projected to hit 105 and San Jose expected to reach 101.
Temperatures may slightly decline on Thursday as the high pressure weakens, yet many inland areas are still expected to remain in the 100s. By Friday, temperatures in the 90s may cover a broader range of areas, and conditions above normal are forecast to continue through the weekend, with San Francisco experiencing daytime highs in the 80s.