The first major rainstorm of the season hit the Bay Area on Monday, causing flash flood warnings and flight delays.
Dylan Flynn, a meteorologist with the National Weather Service’s Bay Area office, said the rain fell mostly within a six-hour period, which caused more flooding than anticipated in the region.
“Almost everywhere got a really good shower for at least 30 minutes or so, followed by a few hours of steady rain across the entire Bay Area and then even into the Central Coast,” Flynn said.
Rainfall totals across the region varied, with Mill Valley recording 0.43 inch of rain, while parts of the Santa Cruz Mountains hit nearly 3 inches. San Jose, which is normally protected from the brunt of heavier rains thanks to the Santa Cruz Mountains, saw a deluge, according to Flynn. At the San Jose Airport, 1.52 inches of rain was reported, which is about three times the normal monthly rainfall for October. It was the second-rainiest day on record for San Jose for the month of October.
“Those records go back over 100 to 125 years,” Flynn said. “Pretty rare to get that much rain.”
The storm first arrived in the North Bay, with 1.13 inches falling in Santa Rosa and 0.71 inch of rain landing in Petaluma. A flash flood warning was issued by the weather service for the Pickett Fire burn scar on Monday near Calistoga.
In San Francisco, the bulk of the storm arrived after 1 p.m. on Monday, and the city saw about 0.75 inch of rain, falling through the afternoon. Oakland recorded 2.14 inches of rain over 24 hours, with other East Bay cities seeing lower totals. Dublin recorded 1.34 inches of rain, and Livermore had 1.25 inches.
Outside the Bay Area, Ben Lomond in the Santa Cruz Mountains saw just under 3 inches of precipitation, according to Flynn.
On Tuesday, there are still some scattered showers in the forecast, and no serious accumulation is expected. But Flynn warned that Bay Area residents may still want to keep an umbrella handy.
“If you get hit with one of these showers, even though they’re smaller in aerial coverage, they could still be strong individually,” Flynn said. “If you get unlucky, you could get a rain shower that follows you around today.”