Swell Matrix

Area Forecast Discussion

National Weather Service San Francisco CA

535 pm PDT Fri jul 17 2026

Short Term

, Issued at 1225 PM PDT Fri Jul 17 2026 (This evening through Saturday night)

A marine layer around 1,200 feet in depth resulted in inland intrusion of stratus overnight. That said, current satellite trends are show these clouds doing their typical afternoon retreat to the coast. Afternoon temperatures will be as much as 10 deg F below seasonal average, especially in the lower elevations.

Overnight, expecting stratus to return to the coast this evening and penetrate into the inland valleys into early Saturday morning. This is typical for the month of July. Once low clouds retreat back to the coast by mid-to-late morning on Saturday, mostly sunny skies are forecast for the afternoon highs again slightly below average. Rise and repeat for Saturday night.

Long Term

..issued at 1225 PM PDT Fri Jul 17 2026 (Sunday through next Thursday)

Still keeping an eye on conditions late this weekend into early next week as there is some uncertainty with regards to the placement of the ridge to the east and troughing to the west. The location of these feature will ultimately drive how much mid-to- upper level moisture we receive from the tropics and monsoon. We will continue to monitor this moisture and Convection-Allowing Models (CAMs) over the weekend to see if their are any singles for convection. Be sure to check back for the latest forecast information.

Aviation

(00z TAFS) Issued at 431 PM PDT Fri Jul 17 2026

Stratus is rebuilding along the coastline and is expected to reach most sites tonight. Moderate confidence that CIGs will be MVFR with IFR possible along the coast as the marine layer deepens to around 1000-1200 ft. Guidance indicates LIFR CIGs are possible right along the coast but confidence is low given the depth of the marine layer. Winds decrease overnight before moderate onshore winds return tomorrow afternoon/evening.

Vicinity of SFO, VFR with stratus and MVFR-IFR conditions returning late this evening. Stratus may filter in as early as 04Z but will most likely return closer to 06Z. Expect clearing by mid to late morning with stratus returning tomorrow evening. Diurnally breezy onshore winds continue.

SFO Bridge Approach, Similar to SFO.

Monterey Bay Terminals, MVFR-IFR conditions expected tonight with some potential for fog to develop early Saturday morning. Confidence is low that fog will develop due to the deeper depth of the marine layer. Initial guidance indicates clearing at SNS by 18Z with a slightly later clearing (20Z) at MRY. Models again show the potential for MRY to remain overcast throughout the day so this may need to be amended.

Marine

(tonight through next Wednesday) Issued at 431 PM PDT Fri Jul 17 2026

Moderate northwesterly breezes will continue to ease through this afternoon and evening. Small craft advisory conditions will gradually taper off this afternoon and evening across most areas with exception to the waters north of Point Reyes and along the immediate coast south of Point Pinos. Moderate to rough seas will persist through today. Conditions improve Saturday as seas abate and northwesterly winds diminish.

Watches, Warnings, Advisories

Ca, None. PZ, Small Craft Advisory until 9 PM PDT this evening for Pt Arena to Pt Reyes 0-10 nm.

Small Craft Advisory until 3 AM PDT Saturday for Pt Arena to Pt Reyes 10-60 NM-Pt Pinos to Pt Piedras Blancas 0-10 nm.

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