A high pressure system centered off the coast of Southern California that has been responsible for some interesting storm patterns has been slow to loosen its grip on Bay Area weather this week, as has been evident in recent weather, or perhaps more accurately, unnoticeable.
Under the influence of the high pressure system, weather conditions have changed little from day to day, but this weekend that is starting to change.
The northern edges of the ridge have begun to give way, reducing pressure aloft and changing wind direction. This is helping to trigger widespread cooling across the region, albeit slowly so far.
But this cooling will accelerate by Sunday and continue for most of next week, with maximum temperatures getting a few degrees cooler each day. By Tuesday, even in the normally warm inland valleys, there will be few places with temperatures above 32 degrees.
During this transition period, weather conditions should be fairly seasonal and pleasant for weekend outdoor activities. Daily clouds and fog will keep the city cool, requiring attendees to wear layers of clothing at the Outside Lands music festival in San Francisco’s Golden Gate Park. Water temperatures in the bay are generally around 60°F (15°C), which will help keep communities along the coast slightly warmer than the west side of the city.
However, the best weather will probably be reserved for inland areas and away from the water’s influence. Inland there will be plenty of sunshine and temperatures between 27 and just under 30 degrees on both weekends.
San Francisco and Peninsula Coast: Over the weekend, morning clouds and fog will be slow to dissipate on the west side of the city, including Golden Gate Park. In fact, there may not be much sunshine west of Twin Peaks. Even where there is sunshine, temperatures will remain cool and winds will be gusty at times. Highs on Saturday and Sunday will be in the high 10s near the water and between 15 and 20 degrees everywhere else, with winds from the southwest at 10 to 20 mph. Clouds are expected overnight, with lows between 10 and 15 degrees.
East Bay: Saturday will likely be the last noticeably hot day inland in the East Bay. Highs in Concord, Walnut Creek and Livermore will reach 35 to 40 degrees on Saturday before falling back to the 25s on Sunday. Daily cloud cover and fog in the morning and late afternoon will keep things a bit cooler in Oakland, Berkeley and Fremont, where highs will range from 18 to 24 degrees. Gusty winds will blow along the water and through the inland passes at 10 to 20 mph.
North Bay: A similar daytime temperature trend will be seen in the North Bay. Temperatures in Santa Rosa, Petaluma and San Rafael will be in the 30s and 35s on Saturday. On Sunday, temperatures in these locations are expected to be in the 25s, except for Santa Rosa, where temperatures will rise to 32s. In coastal areas, where daytime temperatures will be in the 15s and 21s, clouds will clear slowly in the morning and return quickly in the afternoon. Overnight hours will be partly cloudy with lows in the 10s and 15s.
South Bay and Peninsula Bayside: On Saturday, morning clouds should clear fairly quickly across much of the Peninsula and Santa Clara Valley, except for places like Daly City, where cloud cover may linger throughout the day. Highs will range from 65 to 77 degrees in South San Francisco and 79 to 80 degrees in Redwood City. In San Jose, highs will be between 80 and 85 degrees. Cloud cover should be a little more widespread Sunday morning, and the afternoon will be mostly sunny. Highs will also be a few degrees cooler, ranging from 65 to 77 degrees.
Reach Greg Porter: [email protected]
