Bay Area's warm rain, mugginess to be replaced by hot-and-dry conditions

"The forecasts early Wednesday morning indicate temperatures in the hottest places Concord, Livermore and Morgan Hill will rise into the low to mid-80s by Sunday and the low-to-mid 90s by Monday. Those projected figures could go up. It will be a significant uptick following high temperatures of 76, 75 and 75 in those three cities on Wednesday. Still, it felt hotter than that; the humidity ran no lower than 70% throughout the region Wednesday."

"The underlying reason for the humidity, according to weather experts and the weather service, has been a marine heatwave a significant increase in ocean temperature. The marine heat wave that the weather service currently is tracking started in May and covers an area from Southern California up past Canada toward the Alaska Gulf. What it means for the longer-term weather this fall and winter remains to be analyzed."

"That it came on a day when it rained enough for daily records to be set 0.41 inches fell in San Jose and .11 inches fell in Half Moon Bay, breaking marks from 2003 and 1978, respectively only reinforced just how unusual a September storm it's been. No question about it, Hoang said. The warmer-than-usual storm had a chance to drop a bit more rain Thursday in areas of Marin and Sonoma County but it's not expected to accumulate, Hoang said."

An unusually warm, humid September storm brought record daily rainfall to parts of the Bay Area while producing persistently high humidity. Temperatures are forecast to rise sharply, with Concord, Livermore and Morgan Hill reaching low-to-mid 80s by Sunday and low-to-mid 90s by Monday, accompanied by much drier air. San Jose recorded 0.41 inches and Half Moon Bay 0.11 inches, breaking longtime records. The East Bay and South Bay are unlikely to receive additional rain, while minor Thursday accumulation was possible in parts of Marin and Sonoma. A marine heatwave that began in May has elevated ocean temperatures from Southern California to the Alaska Gulf and produced dew points in the 60s. The implications for fall and winter weather remain uncertain.

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