1 month ago
San Francisco Chronicle
Bay Area residents will be waking up to bitter cold temperatures this Saturday, but thankfully this freezing air will drift away later this morning. A warm high-pressure system will take its place. This system will drain warm air across the region, quickly flowing into all the inland valleys of the Bay Area this afternoon.
The end result? A comfortable day across the region, with daytime temperatures in the mid- to upper 60s and a few valleys lucky enough to see highs reach 70 degrees.
This high-pressure system will create an effect where northeast winds will blow over the Diablo Range and spill directly into the valleys and foothills of the East Bay and South Bay. These winds will then spread downhill and into cities like Walnut Creek, Oakland and San Jose, clearing out any clouds in the region and raising temperatures.
Baron Lynx
This warming effect will raise highs along the coast to the lower 60s, while valleys closer to the Diablo Range wil see their temperatures rise to the upper 60s.
The hi-res weather models are signaling around a 60% chance that San Jose and towns in the Santa Clara Valley will briefly reach 70 degrees this afternoon. Depending on the timing of the warm winds, it may just happen. But sunset will still be relatively early – 5:49 p.m. This means that the warmest air out of this system will need to roll in just before sunset, and weather models are expecting it to reach San Jose between 5 p.m. and 6 p.m.
Region-wide temperatures will begin falling immediately after the sun goes down, so if the high-pressure system misses its mark, then San Jose and the Santa Clara Valley will stay just below 70. We’ll just have to wait and see if that 70-degree-air manages to break through.
San Francisco: A cold morning with lows near 40 degrees will quickly make way for a much warmer afternoon. The European weather model forecasts that warm air off a high-pressure system will raise daytime highs to the 60 degree mark in the Sunset and Richmond districts, Lake Merced and the Presidio. Residents east of Sutro Tower will enjoy a warm breeze off the hillsides that will raise temperatures to the lower 60s, with a chance for mid-60s in wind-sheltered and sunny neighborhoods like Mission-Dolores and Glen Park.
Look for mostly sunny skies and warm temperatures citywide on Saturday. After sunset, temperatures will stay above 40 degrees across the city and only drop to the mid-40s on the west side, making for a cozy night.
Pacific Coast and Peninsula: Light northwest winds will blow in from the Pacific Ocean this morning, spreading east from the Half Moon Bay and Pacifica coastlines to the San Bruno Gap. This breeze will keep the coast on the cooler side while warm, dry air allows for sunnier skies to set up shop this afternoon.
This weekend’s warming trend will raise Saturday’s daytime highs to the lower 60s on the coast and the mid-60s farther inland. Daly City and San Francisco International Airport will be some of the warmest spots thanks to the sunshine, while residents downwind of today’s breeze – cities along the 101 corridor south of Millbrae like Redwood City, Foster City and Atherton – will likely stay in the lower 60s.
The warmer daytime weather will also translate into warmer nighttime weather, as overnight lows along the 101 corridor between Daly City and Palo Alto only fall to the lower 40s by Saturday night. A similar trend is on tap for the coast as nighttime lows settle around the mid-40s tonight.
North Bay: Residents in Petaluma, Santa Rosa and Napa valleys – along with some of the summits in the Marin Headlands – are in for a warm and mostly sunny Saturday, with daytime highs climbing to the upper 60s this afternoon.
A high-pressure system will stomp out any chances for morning fog and drizzles in Napa and Sonoma counties, leading to patches of daytime highs just shy of 70 degrees across inland towns like Healdsburg, Guerneville and Calistoga. Residents immediately near the delta, Marin County’s banana belt and in Solano County will be 2 to 3 degrees on the cooler side thanks to a light breeze off San Pablo Bay.
Be sure to carry a warm jacket or hoodie if you plan to be out after sunset. Weather models expect a big temperature swing once the warm winds drop off this evening. This means cities where temperatures reach the upper 60s this afternoon will still be dealing with nighttime lows in the mid- to upper 30s tonight.
East Bay: Weather models are forecasting a warm up across Alameda and Contra Costa counties today as a high-pressure system makes way for ample sunshine.
Weak winds will drain into Castro Valley and Hayward over the next few days, raising temperatures along the I-80/I-880 corridors. Look for daytime highs in the mid-60s across cities like Alameda and Fremont, while mid- to upper 60s settle over the Berkeley and Oakland hills. The warmest temperatures will be in the San Ramon and Livermore valleys, where Walnut Creek, Lafayette and Dublin will enjoy daytime highs in the upper 60s. Thanks to dry air from the high-pressure system and abundant sunshine, the hills east of the Caldecott tunnel I-680 could even reach the lower 70s this afternoon.
But the warm, sunny weather will also be juxtaposed with tonight’s cold temperatures. Weather models are forecasting nighttime temperatures below 40 degrees across most of the inland valleys east of I-680, while lower 40s will settle over cities immediately along San Francisco Bay.
South Bay and Santa Cruz: A high-pressure system will set up north of the Santa Clara Valley and the Santa Cruz Mountains today. This dry system is forecast to raise warm winds, resulting in ample sunshine and comfortable daytime temperatures this holiday weekend.
Look for daytime highs in San Jose, Milpitas and Sunnyvale reaching the upper 60s this afternoon, with chances for lower 70s on tap for downtown San Jose, East San Jose, Morgan Hill and Los Gatos. Heading south along the 101 corridor to Santa Cruz, the light breeze off Monterey Bay will keep coastal areas around 2 to 3 degrees cooler. But expect plenty of sunshine along the coast, including cities like Santa Cruz, Aptos and Capitola.
Just don’t forget to take a warm jacket or hoodie with you if you plan to be out late, because nighttime lows are slated to fall to the lower 40s on the coast and upper 30s farther inland.
Reach Gerry Díaz: [email protected]; Twitter: @geravitywave
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