textproduct: San Francisco Bay Area

KEY MESSAGES

Updated at 1229 AM PDT Fri Mar 13 2026

- Above normal temperatures and minor HeatRisk continue through Saturday

- A sharp warm-up Sunday through Monday will kick off an early season heat wave with record breaking temperatures and moderate HeatRisk next week

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

UPDATE

Issued at 901 AM PDT Fri Mar 13 2026

Locally foggy conditions along the coastline are beginning to dissipate with visibility to improve through the remainder of the morning. Increased cloud cover across the region has kept temperatures this morning a few degrees cooler than they were at this time yesterday. Still expecting highs today to be 10-15 degrees above normal with most interior locations in the mid to upper 70s. Minor HeatRisk is forecast across the CWA today which primarily effects those who are extremely sensitive to heat or without access to cooling/hydration.

SHORT TERM

Issued at 1229 AM PDT Fri Mar 13 2026 (Today and tonight)

Cirrus clouds are moving over the CA coast associated with a sharp upper level trough over the Eastern Pacific. This feature is producing southerly winds that are pumping upper level moisture from the tropics to the West Coast. These clouds will likely remain trough the day as the trough slowly weakens and meanders a little closer towards the coast. This will help moderate the temperatures today, but the moderate strength upper level ridge will keep max temperatures similar to yesterday and around 10-15 degrees above normal.

LONG TERM

Issued at 1229 AM PDT Fri Mar 13 2026 (Saturday through Thursday)

Saturday's temperatures will be similar to Friday, but for a different reason. The high clouds will clear, but a very weak disturbance will take a quick bite out of the ridge. 500mb heights are expected to drop from around 5850m on Friday to around 5770m on Saturday morning. That's still well above normal (5650m) for this time of year. The ridge starts to rebuild Saturday afternoon while surface high pressure builds over the northern Rockies causing the winds to veer offshore. This upper level ridge will continue to build through Tuesday, eventually becoming as strong as we ever seen in March. Some high clouds are likely to return Sunday before clear skies and unfiltered heat moves in for the peak of the heat wave starting Monday. Tuesday and Wednesday look like the hottest days before the ridge axis moves through. This will cause the temperatures to drop a couple degrees, but the heat wave will persist through the workweek. More noticeable relief will have to wait until the weekend, but temperatures may not return to normal for the rest of the month.

The guidance on the strength of this heat wave is remarkable. I'm going to cover it in detail here, but the bottom line is that I audibly gasped when I saw the ECMWF Extreme Forecast Index for maximum temperatures next week. I have never seen it anywhere near this aggressive with bright red painted across the state. That means the ECMWF ensemble members are showing a 99-100% chance of exceeding the maximum values of M-Climate (20-year database). The upper level support strongly points record breaking heat. There is a 75% chance that the 500mb height will break 5900m Monday evening (March record: 5885m). There is also a 75% chance the 850mb temp will break 20C Tuesday - Wednesday (March record: 19.2C). The 250 mb height is very likely to set a monthly record as well. All of this upper level support, combined with offshore winds, creates the perfect recipe for record breaking heat. As such, we expect a slew of daily records to be broken, and several monthly records are likely to go down as well. One final note on the upper level statistics before the hype train runs off the rails; these numbers are very high for March (near the lowest heights climatologically), but would be typical for early August. As such, expect next week to feel like early August, just without the marine layer.

So what does this mean for you? Temperatures will be warm but comfortable through Saturday with mid to upper 70s inland and upper 60s along the coast, roughly similar to what we saw on Thursday. By Sunday temperatures jump 5-10 degrees before another similar increase Monday. During the peak of the heat wave on Tuesday and Wednesday, most areas will be in the upper 80s and 90s, including many coastal locations thanks to the offshore winds. Temperatures will likely drop a couple degrees later in the week, but not nearly enough to end the heat wave. Much of the area will be under moderate HeatRisk. This level affects people sensitive to the heat, especially those without access to cooling and hydration. Keep in mind this is our first heat wave of the year and we haven't seen these temperatures since September.

AVIATION

(12Z TAFS) Issued at 435 AM PDT Fri Mar 13 2026

Upper level moisture riding the ridge is leading to widespread cirrus over the region this morning (SCT-BKN150-250). As the surface, a quasi-marine layer trying to reforming, but it is struggling. VFR most terminals this morning except HAF/MRY with stratus and STS with some patchy fog. Some stratus will linger for HAF, but elsewhere will be VFR today. Stronger onshore flow will lead to some breezy conditions at times. Expect a repeat again tonight into Saturday with some marine stratus impacting the immediate coast and pushing locally inland.

Vicinity of SFO...Breezy NW flow through the GAP with a few low clouds around 500 ft thru AM rush. VFR this afternoon. Didn't buy in on cigs for tonight, but guidance does have some lower cigs with a 20-25% chc of MVFR conditions.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Low/patchy cigs for MRY. There will be pockets of clearing through 17Z at times. Low cigs again tonight for MRY.

MARINE

(Today through Wednesday) Issued at 901 AM PDT Fri Mar 13 2026

Fresh to moderate north/northwest breezes will persist through the weekend. Periods of stronger winds will result in locally hazardous conditions. Both winds and seas will begin to ease late Sunday night into the beginning of next week.

CLIMATE

Issued at 614 PM PDT Thu Mar 12 2026

The following are the record high temperatures at the long term sites for March 15th, 16th, 17th and 18th.

Location Mar 15 Mar 16 Mar 17 Mar 18

Santa Rosa 88 in 2004 91 in 2004 87 in 1996 84 in 2010 San Rafael 83 in 1972 87 in 1972 84 in 1972 80 in 1996 Kentfield 85 in 2004 86 in 2004 87 in 1914 89 in 1914 Napa 86 in 2004 88 in 2004 92 in 1914 87 in 1914 Richmond 85 in 2004 84 in 1972 83 in 2004 78 in 1996 Livermore 83 in 1972 88 in 1972 87 in 1972 86 in 2004 San Francisco 82 in 2004 85 in 1914 85 in 1914 86 in 1914 SFO Airport 81 in 2004 82 in 2004 82 in 2004 77 in 2004 Redwood City 84 in 2004 84 in 2004 85 in 2004 84 in 2004 Half Moon Bay 74 in 1974 78 in 1972 83 in 2004 75 in 1978 Oakland Museum 85 in 2004 85 in 2004 85 in 2004 81 in 2004 San Jose 82 in 2004 85 in 1914 88 in 1914 87 in 1914 Salinas Airport 83 in 1972 87 in 2004 87 in 2004 84 in 1960

MTR WATCHES/WARNINGS/ADVISORIES

CA...None. PZ...Small Craft Advisory until 3 AM PDT Sunday for Pt Arena to Pt Reyes 0-10 nm-Pt Pinos to Pt Piedras Blancas 0-10 nm.

Small Craft Advisory from 3 PM this afternoon to 3 AM PDT Sunday for Pt Reyes to Pigeon Pt 0-10 nm.

Small Craft Advisory from 9 PM this evening to 3 AM PDT Sunday for Pigeon Pt to Pt Pinos 0-10 nm.

Small Craft Advisory until 9 PM PDT Sunday for Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 10-60 NM.