Bay Area temperatures surge into the 70s again

After a month of major changes in weather conditions, the Bay Area is ending February with a brief spring heat wave. Temperatures will climb into the 60s and 70s on Friday and Saturday, then return to normal on Sunday.

It’s a fitting ending for mixed weather conditions. February started out dry and warm, started out wet and stormy, and will now end with some of the warmest readings of the month.

Recent foggy mornings were a reminder of how quickly the atmosphere can turn here. The subtropical moisture cloud targeting the region kept humidity high and allowed shallow fog to form easily throughout the night. But that moisture has now shifted north of San Francisco, increasing the likelihood of fog in the North Bay valleys while allowing most other areas to wake up clearer.

Friday is the prominent day.

The shallow marine layer combined with gentle offshore flow will allow temperatures to warm rapidly. Highs will move into the 70s across much of the Bay Area, including nearshore areas. The interior parts of the South Bay and East Bay can run into 80 degrees. It will feel more like early April than late February.

Saturday will remain mild but will lighten a few degrees as high clouds increase ahead of the weak storm system. This system will drift into Northern California late Sunday and early Monday, dropping temperatures toward seasonal averages and bringing more cloud cover.

Rain chances for the Bay Area remain low overall, but the North Bay and coastal areas will have the best opportunity for light showers from Sunday afternoon through early Monday morning.

As February draws to a close, we can expect the final numbers not to stray too far from the norm, despite the weather conditions. Most Bay Area cities will finish the month about 1 to 3 degrees above normal. The biggest departures occur along the Peninsula coast, where early heat pushes places like Half Moon Bay above 70 degrees for three consecutive days.

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Precipitation totals are also slightly above average in many spots. San Francisco, Oakland and San Jose are on track to end the month about a half-inch wetter than normal.

weekend view

SanFrancisco: Friday is the hottest day. Morning clouds will linger, but highs will climb into the mid-60s along the west side and near 70 in downtown and the Mission. Friday night will be warm and mostly cloudy, with lows in the mid to upper 50s. Saturday will bring a mix of sun and clouds and some cooler weather. Highs will settle into the 60s citywide. Saturday night will again be mostly cloudy with lows in the mid-50s. Sunday will be cooler and grayer. Highs will be in the lower 60s under mostly cloudy skies.

North Bay: Valleys will start out gray on Friday, with patches of heavy fog likely around Santa Rosa, Petaluma and Napa in the early hours; but when the fog rises, temperatures will rise rapidly. Highs will range from the mid-60s near the Marin coastline to the mid-to-upper 70s inland. Friday night will remain partly cloudy, with fog developing again after midnight and lows reaching the 50s. More fog will set in in the valley before a partial clearing on Saturday. It is expected to remain mild, although a few degrees colder than Friday; Highs will be in the mid 60s to low 70s. Winds will be out of the west at 10 to 15 mph in the afternoon. Saturday night will be cloudy again with some fog and lows in the upper 40s to mid 50s. Sunday looks mostly cloudy and cooler with a chance of light showers late in the day. Highs should range from the 50s near the coast to the 60s inland.

East Bay: Friday starts bright and warms up quickly. Highs will reach the mid-70s from Oakland and Berkeley to Walnut Creek and Pleasanton. A few interior points will run at 80 degrees. Friday night will remain mostly cloudy and warm, with lows in the mid-50s. Saturday will start sunny before the clouds increase. Highs will be in the mid 60s to lower 70s. Saturday night will be mostly cloudy with lows in the lower 50s. Market trends are cooler and greyer. Highs will remain in the mid-60s under mostly cloudy skies.

Pacific Coast: Friday is surprisingly warm along the coast for late February. After a partly cloudy start, highs will drop into the lower 70s in Pacifica, Half Moon Bay and Daly City. Light northern winds will keep the sea effect under control. Friday night will remain mostly cloudy and warm, with lows in the mid-50s. Saturday will continue to be pleasant but will drop back a few degrees with sun, clouds and highs in the upper 60s. Sunday looks cooler and grayer; highs in the lower 60s. A slight chance of rain is expected late Sunday night.

Peninsula: Friday is hot for places like Redwood City and San Mateo. After a partly cloudy morning, highs will dip into the mid-70s as light north winds keep the gulf breeze in check. Friday night will be partly cloudy and warm, with lows in the mid-50s. Saturday should start sunny before the clouds increase. Highs will settle into the mid-60s to lower 70s and a light west breeze will develop in the afternoon. Sunday will be cooler and calmer. Mostly cloudy skies will remain with highs in the mid 60s.

South Bay: Rapid warming is expected in Silicon Valley on Friday. Highs will reach the upper 70s in San Jose and Santa Clara, and Gilroy will run around 80 degrees. Friday night will be partly cloudy and warm, with lows in the mid-50s. Saturday will be mostly sunny but a little cooler with highs in the mid-70s. Saturday night will be mostly cloudy again, with some fog possible and lows in the lower 50s. Sunday will be sunny and cloudy, with highs dropping into the mid-60s.

This article was first published at: Bay Area temperatures climb back into the 70s — here’s how long it’ll last.