Swell Matrix

Area Forecast Discussion

National Weather Service San Francisco CA

947 pm PDT Sat may 23 2026

Short Term

, Issued at 1028 AM PDT Sat May 23 2026 (This afternoon through Sunday)

Another deep marine layer setup with plenty of cloud cover pushing inland this morning. The passing weak low pressure will keep stratus mixing around the coast, but the areas inland will see the lower clouds erode quickly in the Sun.

The North Bay looks to keep cloud cover longer than previous days due to this low, leading to a delayed warm up for the interior valleys and overall cooler conditions.

Highs today will range from the 50 along the coast, 60s for areas more inland, 70s for the more interior areas, and into the lower 80s for the far interior. This will be coupled with a fair amount of humidity retention during the day, and great recoveries overnight. The deep marine layer and more of and inland push of the marine air will keep most of the overnight lows in the 50s, with only the far interior falling into the 40s.

Sunday will offer largely similar conditions, with slightly earlier clearing times for that inland North Bay cloud cover. Overall high temperatures will be slightly cooler, but only by a few degrees.

Long Term

..issued at 1028 AM PDT Sat May 23 2026 (Sunday night through next Friday)

The marine layer deepens into Sunday night and will push even farther inland by Memorial Day, leading to widespread cloud cover. This will also cause slower clearing for the interior, and the potential for little to no clearing along the coast. Expect cool coastal conditions under cloudy skies with highs in the 50s. Then the areas slightly inland will hover around the mid to lower 60s, and the far interior will be in the 70s. Only a few portions of the far interior look to break 80.

The next pattern change looks to arrive Tuesday with a low pressure moving down the coast. Longer models have slight disagreements on the track of this low, and unfortunately those differences affect the Bay Area a good amount. If this low pushing inland to the north of the Bay Area, dry off shore flow will cause a jump up in temperatures, not to hazardous levels, but a notable increase. If the low focuses over the SF Bay, chances for drizzle along with continued cooling. The there's a chance the low builds far inland and becomes a cut-off low, giving a uniform, yet weaker, offshore flow. The current forecast follows the first resolution listed, leading to a warmer Tuesday for the Bay Area, but continued cooling for areas to the south. This will be followed by a warming and drying trend for the rest of the work week. Luckily, after that initial jump in temperatures, the rest of the warming trend looks to be gradual. But much can change in the mid to long term forecast, so be sure to keep checking in!

Aviation

(06z TAFS) Issued at 930 PM PDT Sat May 23 2026

Bay Area terminals and South Bay terminals will continue to be VFR until after midnight when MVFR cigs will develop and persist through late Sunday morning. Guidance provides confidence that cigs will mostly be MVFR or hover near it, like KSTS is at issuance time. Timing for MVFR to VFR is less confident, with guidance suggesting MVFR cigs may persist into Sunday afternoon. Breezy onshore flow will persist through the TAF period for near coastal sites.

Vicinity of SFO, VFR will continue until after midnight when MVFR cigs are expected to develop and persist through late Sunday morning. Confidence on timing is better for KSFO and KOAK than other sites. Breezy onshore flow will persist through the TAF period.

SFO Bridge Approach, Similar as SFO.

Monterey Bay Terminals, MVFR cigs will persist through at least late morning, however there is a chance that MVFR cigs persist through the entire TAF period with breezy onshore flow as well. Another otter eddy is expected to develop just offshore of the North Bay early Sunday morning, but then drift farther offshore and north with Monterey Bay not seeing any influence and potential help in clearing.

Marine

(tonight through next Friday) Issued at 930 PM PDT Sat May 23 2026

Light breezes and diminished seas will persist through through Tuesday. Strong northwesterly winds from a developing system set to arrive on Tuesday will result in building rough seas for the second half of next week.

Watches, Warnings, Advisories

Ca, None. PZ, None.

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