textproduct: San Francisco Bay Area

KEY MESSAGES

Updated at 952 AM PDT Sat Apr 25 2026

- Isolated, light showers through Sunday

- A warming and drying trend next week

SHORT TERM

Issued at 952 AM PDT Sat Apr 25 2026 (This afternoon through Sunday)

An upper level low roughly 200 miles west of the Monterey Bay will approach the coast over the next 12 hours. This system is bringing widespread overcast skies, some very light rain, and cooler temperatures today. Below this upper level disturbance, we also have a deep marine layer impacting the surface conditions. The 12Z balloon measured the depth at nearly 4,000 feet capped by a very strong inversion. Between the moist marine layer and upper levels, there is a layer of very dry air between 800 mb and 600 mb, where the average relative humidity is less than 5%. This dry layer will cause much of the rain to evaporate before reaching the surface today. So far we've recorded 1/100th inch of rain in a few different rain gauges throughout the Bay Area and Central Coast. Rain will generally fall as light and brief showers, with the most activity expected in Santa Cruz and Monterey Counties early Sunday morning. All told, we're not expecting to exceed 1/10th of an inch. For Big Sur Marathon runners, this is the type of rain that's nice to run in. The wind will be much weaker than normal years, too.

Anytime there is a landfalling low pressure system we need to take a look at thunderstorm chances. There are a lot of factors working against convection in this environment. The CAPE isn't expected to break 100 J/kg, and even that is all below the inversion where the air is above freezing. That means there won't be any ice particles to create static electricity buildup. Additionally the inversion and very dry mid levels are barriers to coherent updrafts. While the NBM shows a 5% chance of thunderstorms today, that may be on the high side. Chances may be marginally better tomorrow as the dry layer becomes more saturated, but we're still well below 10%.

After the upper level front moves through Sunday, much drier air will filter in, clearing the mid and upper level clouds by Sunday afternoon. The marine layer rarely gets much deeper than 4,000 feet, and it's unlikely to survive as the low moves overhead. That should help mix out the low clouds as well. So the sun should come out tomorrow, but the temperatures will still be stuck in the 60s until the 850 temps recover through the week.

LONG TERM

Issued at 952 AM PDT Sat Apr 25 2026 (Sunday night through next Friday)

A warming and drying trend will start Monday and continue through the week as the 500 mb trough gradually transitions into a ridge. Temperatures will climb a few degrees each day, eventually reaching mid to upper 70s by Wednesday across the interior, and remaining there into the weekend. The marine layer will start to reform under the ridge, keeping coastal areas in the 60s through the week. In other words, it will be a pretty nice week. It's hard to say what will happen the following week, with ensemble clusters split roughly evenly on a continued ridging pattern or the return of another trough and unsettled weather.

AVIATION

(18Z TAFS) Issued at 1047 AM PDT Sat Apr 25 2026

Currently a mixed bag of MVFR-VFR at the terminals. Conditions will continue to improve through the morning with low-end VFR/high-end MVFR ceilings expected through the TAF period. There's a chance for drizzle and/or light rain showers through the TAF period. The best chances are tomorrow morning as a surface trough passes through - coastal locations will be favored. Southwesterly winds will prevail through the TAF period with gusts up to 25 knots possible at exposed terminals.

Vicinity of SFO...Currently VFR with westerly flow. Moderate confidence on VFR through the TAF period with up to a 60% chance for an MVFR ceiling to return tonight. If it does return, it'll likely be in the FL025-FL030 range. Winds will strengthen and back this afternoon to become southwesterly. Westerly winds return tomorrow morning. There's a chance for drizzle and/or light rain showers through the TAF period with the best chances holding off until tomorrow morning.

SFO Bridge Approach...Low stratus below FL040 in the low-end VFR/ high-end MVFR range is expected through tomorrow morning. There's a low probability (less than 30% chance) that it lingers into tomorrow afternoon.

Monterey Bay Terminals...Currently VFR with southwesterly flow at MRY and MVFR with northwesterly flow at SNS. Conditions will continue to improve at SNS through the morning. Low-end VFR/high-end MVFR ceilings will prevail through the TAF period. There's a chance for drizzle and/or light rain showers through the TAF period with the greatest uncertainty being how far north they can make it. The best chance will be this afternoon and again tomorrow morning. Westerly winds this afternoon and evening will back to become southwesterly tonight.

MARINE

(Today through Thursday) Issued at 952 AM PDT Sat Apr 25 2026

Expect mainly moderate west to northwest breezes and moderate seas through the early part of next week. Drizzle and light rain remain in the forecast, favoring the southern waters and areas along the coast this weekend. Strong northwest breezes and rough seas return towards the middle of next week.

MTR WATCHES/WARNINGS/ADVISORIES

CA...None. PZ...None.