Swell Matrix

Area Forecast Discussion

National Weather Service San Francisco CA

641 pm PDT Thu Mar 12 2026

Short Term

, Issued at 238 PM PDT Thu Mar 12 2026 (This evening through Friday)

No major adjustments to the short term forecast. Upper level ridging and high pressure continue to push in along the West Coast with temperatures running 10 to 15 degrees above normal. A glance at the current 1PM observations shows that temperatures are running anywhere from 5 to 10 degrees warmer than they were at this time yesterday. High temperatures today will largely be in the upper 70s to low 80s with coastal locations staying in the 60s to 70s. Minor HeatRisk is expected today across almost the entire CWA. This primarily effects those who are extremely sensitive to heat and lack adequate access to cooling or hydration. If you are working outside or are sensitive to the heat, make sure that you are taking breaks and are drinking plenty of water. San Jose remains the only site forecast to tie their daily record today with a forecast high of 81 degrees. As of 1PM, SJC is reporting a temperature of 71 degrees with several hours of heating to go this afternoon. Temperatures do cool down overnight with lower elevations dropping into the 40s while higher elevations stay in the 50s. This will bring overnight relief from the heat and allow people to cool down.

Long Term

..issued at 238 PM PDT Thu Mar 12 2026 (Friday night through next Wednesday)

A long duration heat event will continue through the extended forecast as upper level ridging and high pressure linger over California. The Long Term forecast can be split into two main distinctions: when onshore flow is present and when offshore flow is present. Winds are predominantly onshore Friday and Saturday before shifting offshore Sunday through the remainder of the extended forecast. Onshore winds will help to mitigate how much temperatures warm Friday and Saturday. This will keep temperatures in the upper 70s to low 80s across the interior and 60s to 70s along the coast. It is worth pointing out that although this is comparatively cooler than what we will see later in the week this is still 10 to 15 degrees warmer than normal for this time of year.

As we head into Sunday, the center of the upper level ridge will be just offshore of the Bay Area and supports winds shifting offshore. This transition is important as it will bring drier, warmer continental air into the region and support further temperature rises. This will allow many of our climate sites (see Climate section below for a list of sites) to either challenge or break their daily temperature records next week. Temperatures across the interior will climb into the upper 80s to low 90s as early as Sunday before becoming more widespread Monday and Tuesday. There is the potential for records to be broken daily Sunday through Wednesday but the locations do vary. Noteworthy spots to watch would be San Jose and the Salinas Airport as both sites are forecast to break their daily records Monday and Tuesday. More coastal sites (San Francisco, Half Moon Bay) may come close to their records but are not currently forecast to break them. At the same time, morning low temperatures also warm next week with lows rising into the mid to upper 50s. This will limit overnight relief from warm temperatures and is a key factor in the return of Moderate HeatRisk Monday and Tuesday. This is our first major heat event of the year and our bodies are still used to comparatively cooler winter weather. It is important to stay hydrated and allow time for rest if participating in outdoor activities on Monday/Tuesday. The current forecast shows temperatures remaining hot at least through Wednesday but likely through Friday.

Another concern with the return of warmer, drier conditions and light offshore winds next week is the potential for small fires/grass fires. Larger fuels are still moist from winter rains but the return of much above normal, hot weather may result in smaller fine fuels (grass) curing faster than normal. Winds are expected to be relatively light which will minimize how much any grass fires that are able to develop can spread. This is primarily important for Prescribed Burns but if you are participating in any outdoor activities for spring break (i.e. camping, hiking, offroading, etc.) make sure to take this into account as well.

Aviation

(00z TAFS) Issued at 641 PM PDT Thu Mar 12 2026

VFR is continuing this evening. 5.3 mb ACV-SFO, 3.2 mb SFO-SMX and 1.0 mb SFO-SAC pressure gradients support ongoing northwest winds. Conditions have improved over the last week for potential night-time and morning coastal stratus/fog; satellite shows the leading edge of stratus moving southward passing by Point Arena. 00z KHAF, KOAK and KMRY TAFs advertise a little more stratus LIFR- IFR ceilings tonight and Friday morning. Inland terminals continue with VFR. High clouds are forecast to increase during the 00z TAFs otherwise coastal stratus/fog is likely to mix out by late Friday morning.

Vicinity of SFO, VFR. West wind near 15 knots decreasing to 5 to 10 knots tonight then increasing to near 15 knots Friday afternoon and evening.

SFO Bridge Approach, Similar to SFO.

Monterey Bay Terminals, VFR through mid to late evening, then increasing probability of patchy stratus and/or fog. Conditions improving to VFR by late Friday morning. Northwest winds near 10 knots decreasing and becoming light southeast tonight and Friday morning. Winds westerly near 10 knots Friday afternoon and early evening.

Marine

(tonight through next Tuesday) Issued at 238 PM PDT Thu Mar 12 2026

Gusty northerly winds continue across the outer waters. Winds will eventually increase for the near shore zones by late Friday. The stronger winds will result in locally hazardous conditions. Winds and seas ease into the next work week.

Watches, Warnings, Advisories

Ca, None. PZ, Small Craft Advisory from 9 AM Friday to 3 AM PDT Saturday for Pt Arena to Pt Reyes 0-10 nm-Pt Pinos to Pt Piedras Blancas 0-10 nm.

Small Craft Advisory from 3 PM Friday to 3 AM PDT Saturday for Pt Reyes to Pigeon Pt 0-10 nm.

Small Craft Advisory from 9 PM Friday to 3 AM PDT Saturday for Pigeon Pt to Pt Pinos 0-10 nm.

Small Craft Advisory until 3 AM PDT Saturday for Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 10-60 NM.

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