textproduct: San Francisco Bay Area

KEY MESSAGES

Updated at 1201 AM PDT Thu Apr 23 2026

- Seasonal temperatures and dry conditions return today

- Potential for rain/drizzle and slightly cooler temperatures this weekend into early next week

- Warming trend begins early to mid next week

SHORT TERM

Issued at 126 PM PDT Thu Apr 23 2026 (This evening through Friday)

Radar is finally quiet this afternoon after a period of somewhat active weather. Visible satellite shows mostly clear skies around the region with a few pop up CU hugging the hills. Increased insolation this afternoon has led to a warmer temperatures across the board.

Stepping back and looking at the longwave pattern over EPAC and CONUS reveals an interesting pattern. The EPAC is highly amplified with a solid ridge extending into E AK and W BC with a low off the CA coast with a rex block vibe. Farther east two pronounced upper lows spin, one north of MT and the other east of Nova Scotia with a ridge smacked in between with an omega block vibe. In other words a little bit of a traffic jam in the upper atmosphere. That being said, we do see some minor movement on the small scale and closer to home. A weak embedded shortwave/fuzzy upper low off the CA coast is slowly moving eastward. As this feature moves eastward high clouds will increase over the region tonight and Friday. The higher clouds may limit fog production tonight, but some low stratus will be possible. Interestingly, some of the CAMs resolve some forecast 1KM radar reflectivity tonight. Forecast is dry for Friday morning, but a few echoes may appear on radar. Increased cloud cover will also lead to cooler temperatures on Friday with highs dropping below seasonal averages again.

LONG TERM

Issued at 126 PM PDT Thu Apr 23 2026 (Friday night through next Wednesday)

A trend that emerged a few days ago is still on track for the upcoming weekend, "wetter" and cooler. Broad troughiness remains over region with re-enforcing upper lows. Another upper low is on track to move over the region Friday night into Saturday and subsequent vort maxes Saturday into Sunday. These features combined with the northern fringes of sub-tropical moisture pulses will lead to some drizzle/light rain showers Friday night through Sunday morning. Not expecting much in the way of accumulation, trace to a few hundredths. Areas most favored will be coastal mts with enhanced low level lift. Temperatures for the upcoming weekend will be below seasonal averages with highs in the upper 50s and 60s.

By early next week 500mb heights begin to rebound with warming 850mb temps kicking off a gradual warming and drying trend. No precip in the forecast Monday through Wednesday.

AVIATION

(18Z TAFS) Issued at 1141 AM PDT Thu Apr 23 2026

Quiet weather with some fair weather cumulus clouds popping up over the region and high clouds passing overhead. VFR conditions will prevail through the evening and perhaps early overnight hours for most sites. Guidance suggests that a mix of stratus and fog will return at some point, but there are some caveats. High clouds could disrupt fog and stratus formation, in addition to winds. Trended towards KAPC and KSTS seeing another night of reduced ceilings and visibility, with KHAF likely joining them. The models are bit divided on the expanse of the stratus and fog, thus I opted to hint at lowering cigs for KSJC and KLVK. Medium to high confidence in the forecast.

Vicinity of SFO...Onshore flow is expected to return this afternoon, and increase to around 15kt around 0Z. This will last into the late evening hours with winds falling below 10kt near or after 7Z. Quite a few models indicate MVFR ceilings moving into the Bay, with much of the Bay seeing MVFR cigs increase between 11-14Z and continuing until at least 17-18Z. Opted to go with a slightly more optimistic forecast with cigs clearing between the 17-21Z. Medium confidence in the forecast.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR conditions prevail for the majority of the region for the afternoon with high clouds streaming overhead and cumulus popping up over the mountains. Much like the discussion above, stratus and any associated fog may be dependent on the high clouds and winds. Guidance shows Monterey Bay with ceilings around 035-050 for heights, though a few bring KMRY closer to MVFR status. Expect this to occur just before or around sunrise, before mixing out by mid to late morning.

MARINE

(Today through Tuesday) Issued at 924 AM PDT Thu Apr 23 2026

Moderate north breezes this morning will develop into a northwest breeze this afternoon. Choppy seas at times today will begin to subside Friday and continue into the weekend. Light rain and drizzle return to this weekend.

MTR WATCHES/WARNINGS/ADVISORIES

CA...None. PZ...Small Craft Advisory until 9 PM PDT this evening for Pigeon Pt to Pt Pinos 0-10 nm-Pt Arena to Pt Reyes 0-10 nm-Pt Pinos to Pt Piedras Blancas 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm.

Small Craft Advisory until 9 AM PDT Friday for Pt Arena to Pt Reyes 10-60 NM.

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