textproduct: San Francisco Bay Area

KEY MESSAGES

Updated at 1247 PM PDT Wed Mar 18 2026

- Early season, long duration heat wave continues to bring record- breaking temperatures and Moderate HeatRisk through Friday

- Elevated potential for grass fires through the week due to warm and dry conditions with periods of moderate offshore winds

- Gradual cooling trend begins this weekend

UPDATE

Issued at 847 PM PDT Wed Mar 18 2026

The forecast remains on track tonight. Numerous daily records were broken today with Richmond breaking their previous daily record by 10 degrees and Salinas airport breaking their daily record by 9 degrees while also setting their new March record, coming in at 93. With the building heat continuing, the warmest nights are still to come, along with more daily and monthly records likely to be set Thursday and Friday. There's a welcome drop in temperatures Saturday around 10 degrees for most locations, with more gradual cooling by Sunday into the beginning of next week.

SHORT TERM

Issued at 1247 PM PDT Wed Mar 18 2026 (This evening through Thursday)

The strong mid/upper level high pressure, that has resulted in several daily and monthly records the past two days, is currently over southern California and the Desert Southwest. As forecasted, the 500 mb height has strengthened to 594 dam with 850 mb temperatures around 23 degrees C. As such, temperatures this afternoon will warm into the upper 70s along the immediate coastline and into the mid 80s elsewhere closer to the coast. Elsewhere, just inland away from the coast and in the interior, temperatures will rage from the upper 80s to lower 90s and potentially the mid to upper 90s the the warmest interior spots. Some locations along the Sonoma and Marin county coastline remain in the 50s as of early this afternoon as low stratus and a shallow marine layer impacts that region.

Tonight into Thursday morning, expecting the coldest interior locations to cool into the upper 40s (mainly in the North Bay) with low to upper 50s in other valley locations. In the higher elevations across the region, we are only expecting mid 60s to lower 70s.

Thursday, we are expecting a degree or two of warming across the board. Please see the CLIMATE section below for additional details on potential record breaking heat.

LONG TERM

Issued at 121 AM PDT Wed Mar 18 2026 (Thursday through Tuesday)

Rinse and repeat through Friday. Expect record breaking heat each afternoon as the ridge of high pressure stalls over the desert SW. Confidence is increasing that the heat wave will start to break on Saturday. Our latest forecast has temperatures dropping around 10 degrees on Saturday, and another 5 on Sunday. That would bring us back into the 70s for most inland areas and 60s along the coast to start next week. By the way, that's still 5-15 degrees above normal for this time of year. As the ridge breaks down there is good chance for stronger winds this weekend, which will bring some additional relief to the hot temperatures, but also brings some enhanced fire weather conditions for fine dead fuels. The next chance for any rain is around the end of the month or early April, but the ensemble members diverge spectacularly by that point, and it's just as likely that another dry heatwave moves in.

AVIATION

(06Z TAFS) Issued at 925 PM PDT Wed Mar 18 2026

VFR will prevail through the TAF period with clear skies and relatively light offshore winds developing overnight. The stagnant airmass may lead to the development of haze with no impacts expected.

Vicinity of SFO...VFR with clear skies and light winds that will eventually become onshore Thursday afternoon.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR with clear skies and light offshore flow overnight. Relatively light onshore flow returns Thursday afternoon.

MARINE

(Tonight through next Tuesday) Issued at 847 PM PDT Wed Mar 18 2026

Gentle breezes continue across the inner waters with moderate north to northwest breezes over the outer waters. Northwest winds will begin to increase Thursday night into Friday and persist through the weekend, with hazardous seas developing by Friday night in response to the strengthening winds.

CLIMATE

Issued at 421 AM PDT Wed Mar 18 2026

The following are the record high temperatures at the long term sites for March 18th, 19th and 20th.

Location Mar 18 Mar 19 Mar 20

Santa Rosa 84 in 2010 83 in 2004 84 in 2004 San Rafael 80 in 1996 81 in 1964 82 in 1960 Kentfield 89 in 1914 83 in 1996 82 in 2001 Napa 87 in 1914 86 in 1914 86 in 2004 Richmond 78 in 1996 80 in 1996 81 in 2004 Livermore 86 in 2004 82 in 2015 87 in 1915 San Francisco 86 in 1914 80 in 2010 78 in 2004 SFO Airport 77 in 2004 78 in 2010 78 in 2004 Redwood City 84 in 2004 81 in 2010 82 in 2004 Half Moon Bay 75 in 1978 79 in 2010 75 in 2010 Oakland Museum 81 in 2004 81 in 1984 78 in 2001 San Jose 87 in 1914 82 in 1988 78 in 2004 Salinas Airport 84 in 1960 87 in 1997 80 in 1934

The following are the record high temperatures at the long term sites for the entire month of March.

Location

Santa Rosa 91 on March 16, 2004 San Rafael 88 on March 25, 1952 Kentfield 91 on March 28, 1923 Napa 92 on March 17, 1914 Richmond 87 on March 31, 2021 Livermore 90 on March 25 and 26, 2025 San Francisco 87 on March 11, 2005 SFO Airport 85 on March 25, 1952 and March 17, 2026 Redwood City 93 on March 17, 2026 Half Moon Bay 83 on March 31, 2000 and March 17, 2004 Oakland Museum 89 on March 17, 2026 San Jose 89 on March 14, 2015 Salinas Airport 92 on March 14, 2015 and March 17, 2026

MTR WATCHES/WARNINGS/ADVISORIES

CA...Heat Advisory until 8 PM PDT Friday for CAZ006-502>506-508>510- 512>518-528>530.

PZ...Small Craft Advisory from 9 PM Thursday to 9 PM PDT Friday for Pt Arena to Pt Reyes 10-60 NM.