Swell Matrix

Area Forecast Discussion

National Weather Service San Francisco CA

1257 pm PDT Wed apr 29 2026

Short Term

, Issued at 1256 PM PDT Wed Apr 29 2026 (This evening through Thursday)

The warming trend continues this afternoon with high pressure building in from the eastern Pacific Ocean. This afternoon will warm into the upper 50s to low 70s near the coast and mid 70s to near 80 degrees F across the interior under mostly clear sky conditions.

Expecting low clouds to return to the coast and locally inland into the coastal adjacent valleys overnight tonight and more so into Thursday morning. This is especially so over the Monterey Bay Region, the San Francisco Peninsula, and through the Golden Gate into Oakland. There is a greater probability of this to occur as the marine layer is forecast to deepen overnight to around 1,200 feet. Overnight lows are forecast to range from the mid 40s (colder interior locations) to lower 50s.

Thursday will feature a few degrees of warming across the interior (up to 6 degrees F above seasonal averages). However, coastal locations will remain will generally remain within a few degrees of normal for late April due in large part to onshore flow and the marine influence.

Long Term

..issued at 1256 PM PDT Wed Apr 29 2026 (Thursday night through next Tuesday)

Temperatures will be warmest Friday afternoon when we have the greatest probability of reaching or exceeding 85 deg F across the interior, with the warmest being across the interior Central Coast (greater than 50%). Temperatures near the coast will remain cooler thanks to onshore flow, coastal stratus, and the marine influence.

A slight downward trend is expected for Saturday as a mid/upper level trough drops down from the Gulf of Alaska and into the eastern Pacific. This will help deepen the marine layer to around 2,000 feet. Thus, expect coastal stratus to penetrate deeper into the valleys on both Saturday and Sunday. This low pressure system will eventually become a cut-off low with high pressure building across British Columbia late in the weekend setting up a Rex block. This would bring drizzle and/or light rain to the coastal waters Saturday night and into Sunday. Then, as the mid/upper level low shifts inland Monday and Tuesday, it will bring increasing chances for drizzle and/or light rain to the Bay Area and Central Coast. The WPC 500 mb height-based cluster analysis shows increasing confidence in this pattern occuring. Rainfall amounts from this system are expected to remain very light, with generally a few hundredths of an inch expected throughout this early week event.

Aviation

(18z TAFS) Issued at 1050 AM PDT Wed Apr 29 2026

The patchy fog has cleared and low clouds have pulled back to the coast. There's high confidence in VFR conditions across all terminals this afternoon, with the exception of HAF. While we expect several hours of VFR conditions there, the stratus deck is expected to hang around just off the coast and could make a surge at any time. Winds will increase to a moderate onshore breeze with the arrival of the sea breeze this afternoon. Low clouds are likely to return overnight as the marine layer continues to become better organized. While we expect a fully formed marine layer by Friday morning, we're still in the transition Thursday morning and the impacts will be more scattered and temporary. As such, the forecast confidence is rather low through the second half of the TAF period.

Vicinity of SFO, VFR conditions through the afternoon and evening. Winds will shift to westerly and increase to a strong breeze over the next few hours. There is a 50-70% chance of MVFR stratus impacts Thursday morning, with the highest likelihood around 15Z. The window of likely impacts is only around 4-6 hours, however, and there's a chance the terminal dodges these ceilings.

SFO Bridge Approach, Similar to SFO.

Monterey Bay Terminals, There's high confidence in VFR conditions through the afternoon. The chance for MVFR impacts steadily increases from 40% at 06Z to 80% by 14Z. If they form, there a 50% chance these ceilings will drop into the IFR category, at least temporarily.

Marine

(today through Monday) Issued at 1050 AM PDT Wed Apr 29 2026

NW winds will increase to a strong breeze this afternoon. These winds will build rough seas of 8 to 12 feet. Similar conditions will persist through Friday before winds start to decrease Saturday and continue improving through the weekend.

Watches, Warnings, Advisories

Ca, None. PZ, Small Craft Advisory until 3 AM PDT Thursday for Pigeon Pt to Pt Pinos 0-10 nm-Pt Arena to Pt Reyes 0-10 nm.

Small Craft Advisory from 3 PM to 9 PM PDT Thursday for Pt Arena to Pt Reyes 0-10 nm.

Small Craft Advisory until 9 PM PDT Thursday for Pigeon Pt to Pt Pinos 10-60 NM-Pt Pinos to Pt Piedras Blancas 0-10 nm.

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

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