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

SHORT TERM

Issued at 105 PM PDT Thu Mar 19 2026 (This evening through Friday)

Definitely a day of nuanced details and micro-climates around the Bay Area and Central Coast. In the big picture it's still hot around the region with temperatures well above for late March. The details however show many locations are running colder than yesterday and some of these locations will fall short of their forecast high temperature. The shallow marine layer from early this morning was enough to cause havoc on max temps with any marine influence. All that being said, did tweak a few temperatures this afternoon, but didn't completely give up on hope for a warm up. A quick shift of the wind direction could allow for a late day bump in temps. The airmass does support it as the OAK sounding was 19.55C at 850mb at 12Z this am.

For tonight through Friday...marine layer from this morning has faded and pretty much dissipated per satellite. Offshore flow is gradually developing just above the surface. This will persist overnight and actually strengthen a bit leading to better mixing and some drying flow in the BL. Hi-res guidance shows this as well with lower moisture at the surface. Some patchy clouds are possible near the coast, but thinking less than last night. Friday will be a transition day as the anomalously upper ridge begins to slowly ease eastward. 500mb heights may decrease slightly, but 850mb will likely reach their peak. As such, inland areas have the potential of seeing some of their warmest temps yet. Just like today however, coastal areas will be tricky again with subtle temp differences due to marine influence late in the day. Will keep Heat Advisory as is for now. Even if a few spots near the coast/bays fall a little short of forecast highs heat impacts are a cumulative effect.

LONG TERM

Issued at 105 PM PDT Thu Mar 19 2026 (Friday night through next Wednesday)

The large area of high pressure continues its eastward push Friday night into Saturday as an upstream trough/cold front moves in. At the surface, local WRF model shows the rebuilding of the marine layer Friday night. The cold front is expected to push through day putting an end to the heat wave and bringing much needed relief. The fropa will bring a 5 to 10 degree drop on Saturday with an additionally 5 degrees on Sunday. Despite the temp drop for Saturday and Sunday, temperatures will still be well above normal for March. Temperatures moderate through the first half of next week, but stay above normal with zonal flow over the region. Previous forecast had precip brushing the N Bay around the 25th of March, but latest guidance continues with a drier solution. If this chance of precip is looking less when does confidence increase? Longer range ensemble forecast show a few members producing rain around the beginning of April. As they say, April showers bring May flowers. We'll see...

AVIATION

(00Z TAFS) Issued at 432 PM PDT Thu Mar 19 2026

VFR for most sites through the TAF period. Winds remain breezy through the early evening before weakening overnight. WRF guidance shows some potential for another shallow (250 ft) marine layer to develop again tonight. The HREF signal is not quite as strong as it was last night but coastal sites (HAF, MRY, potentially SNS) may see patchy stratus development overnight. Onshore winds strengthen again by late tomorrow morning with winds peaking between 10-15kt.

Vicinity of SFO...VFR. Winds are expected to shift onshore this afternoon/evening before weakening and becoming variable/offshore again overnight. LAMP guidance shows a low potential for low lying clouds to develop tonight but confidence is low due to high pressure suppressing the marine layer. Onshore winds strengthen to around 15 kts tomorrow afternoon/evening. Main change to the TAF was to push back the return of onshore winds tomorrow to closer to 00Z as they have been returning later than originally forecast.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Light, onshore winds continue through this evening before winds shift offshore overnight. Low chance of stratus developing at MRY overnight as a shallow marine layer attempts to redevelop. HREF guidance shows a patch of stratus in the Monterey Bay tonight but the cloud cover signal is not very widespread - keeping confidence lower. Winds shift onshore again tomorrow afternoon with breezier conditions expected at SNS.

MARINE

(Tonight through next Tuesday) Issued at 432 PM PDT Thu Mar 19 2026

A gentle to moderate breeze continues across the inner waters with moderate north to northwest breezes over the outer waters. Northwest winds will begin to increase tonight across the outer waters before spreading across the inner waters Friday 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 19 Mar 20

Santa Rosa 83 in 2004 84 in 2004 San Rafael 81 in 1964 82 in 1960 Kentfield 83 in 1996 82 in 2001 Napa 86 in 1914 86 in 2004 Richmond 80 in 1996 81 in 2004 Livermore 82 in 2015 87 in 1915 San Francisco 80 in 2010 78 in 2004 SFO Airport 78 in 2010 78 in 2004 Redwood City 81 in 2010 82 in 2004 Half Moon Bay 79 in 2010 75 in 2010 Oakland Museum 81 in 1984 78 in 2001 San Jose 82 in 1988 78 in 2004 Salinas Airport 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 88 on March 18, 2026 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 93 on March 18, 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 3 PM Friday to 9 AM PDT Saturday for Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 0-10 nm.

Small Craft Advisory from 9 PM this evening to 9 AM PDT Saturday for Pt Arena to Pt Reyes 10-60 NM.