This is the time it will rain in San Francisco
A storm is expected next week during the largest gathering of world leaders in San Francisco since 1945.
The upcoming APEC summit will attract thousands of diplomats, business executives, reporters and others to the Gulf region from Monday to Friday. With an unstable weather forecast, there is a lot of wiggle room for wind and rain chances. Here’s a look at how the weather is likely to play out during what looks to be the region’s first significant rain of the season.
Weather effects
World leaders and visitors can expect nice weather when they arrive in San Francisco this weekend. Signs are that the storm system will remain outside of California through Tuesday, meaning the mild weather typical for this time of year will be on hand for the summit’s first full day. Look for highs Monday in the mid to upper 60s downtown, with light winds off the Embarcadero.
Cloud cover will increase steadily Monday night before the storm brings the first rounds of rain to the Bay Area on Tuesday. Weather models predict a modest range of potential impacts, with a 40% to 50% chance of rain falling throughout much of the region.
Rainfall chances in downtown San Francisco are expected to increase to 80% during the day on Tuesday, with heavy rain possible in the afternoon. Look for a quarter to half an inch of rain by the end of the day, with heavier rain possible around Nob Hill and Soma overnight. Wind speeds could reach 30 mph in the afternoon along Market Street and will likely continue to gust steadily between 20 and 25 mph through the second half of the week.
Wednesday is set to be the wettest day of the week for the San Francisco corridor from the Bay Bridge to 12th Street, as a storm system dumps moderate rain with rainfall rates of up to a tenth of an inch per hour throughout the day. There is a degree of uncertainty as to the timing of the heaviest bands of rain, but expect anywhere from a half-inch to an inch of rain ruining outdoor plans throughout the day.
The storm system is expected to shift course toward Southern California starting Thursday, meaning rain activity should begin to taper off in San Francisco during the second half of the Asia-Pacific Economic Cooperation (APEC) forum. However, heavy rain and 25 mph gusts are possible through Saturday. Look for an additional 1/2 to an inch of rain, and wet conditions to continue through Sunday.
Stay tuned for forecast updates as details on the timing of heavy rainfall become clearer in the coming days.
Contact Gerry Diaz: gerry.diaz@sfchronicle.com; Twitter: @geravitywave
