Swell Matrix

Area Forecast Discussion

National Weather Service San Francisco CA

504 pm PDT Fri Jun 19 2026

Short Term

, Issued at 1248 PM PDT Fri Jun 19 2026 (This evening through Saturday)

Interesting weather setup across the region today and it's a tale of the upper and low portions of the atmosphere. Let's first talk about the lower and more impactful to the Bay Area and Central Coast. A solid marine layer, nearly 3,000 feet, this morning was loaded with ample low level moisture. Orographic lift and subtle broad ascent aloft led to drizzlefest. This was well advertised for several days and this morning was the real deal. Automated gages around the region picked a few hundredths over the last 12 hours, most notably along the coast and coastal mts. As for the upper level portion of the atmosphere: a jet max, a weak shortwave/upper low, and abnormally high PWATs led to showers and thunderstorms north of the Bay Area. We did see a few high clouds clip the N Bay, but better forcing and moisture was to the north.

Given the deep nature of the marine layer and persistent onshore flow several a few spots are struggling to see ample sunshine this afternoon, especially along the coast and N bay. Elsewhere across the interior is seeing Sun this afternoon. Despite the Sun, general consensus across the region shows a slight cooler trend across the region. One final highlight for the nearterm are the winds. The thermal difference from the cloudy coast and inland Sun will lead to another afternoon of gusty onshore flow. Gusts of 20-30 mph seems plausible with local gusts up to 40 mph (gaps/passes).

Tonight through Saturday: Upper level trough along the West Coast and low level onshore flow will usher the marine layer back in. Just like this morning, coastal drizzle will be possible. Saturday day will be very similar to Friday: morning clouds clearing back to the coast, below average temps, and breezy to gusty onshore flow in the afternoon.

Long Term

..issued at 135 PM PDT Fri Jun 19 2026 (Saturday night through next Thursday)

By the end of the weekend we begin to see a shift in the longwave pattern over the West. The upper level trough finally begins to lose its grip and is initially replaced with shortwave ridging Sunday into Monday. Monday and beyond the large upper level ridge currently shunted into Mexico begins to surge north. Therefore 500mb heights begin to rise and 850mb temps warm. What does all of this mean for the Bay Area and Central Coast? The marine layer will begin to compress and temperatures will begin to warming. The trend will be more subtle Sunday into Monday, but therefore after a more marked warming trend will develop. By the middle of next week interior locations will see some packets of Moderate HeatRisk with temps soaring into the 90s. As of now, the forecast does bring some nighttime relief limiting overall HeatRisk concerns. This could change between now and then.

This was noted on the previous discussion and worth noting again. As the upper ridge builds over over the Desert SW next week it then shifts eastward slightly. The eastward shift allows a plume a moisture to surge north on the western periphery of the ridge. Longer range guidance brings the moisture north along Baja on Tuesday and CA Wednesday/Thursday. Good way to describe this scenario is low chance high impact. We don't have anything officially in the forecast for thunderstorms, but we'll need to keep an eye on it.

Aviation

(00z TAFS) Issued at 504 PM PDT Fri Jun 19 2026

Widespread VFR conditions with moderate SW to W breezes (11-15kt) this afternoon. Most terminals have peaked in afternoon gusts with some in excess of 15-20kt. Winds will weaken into the overnight hours. The marine layer will return later this evening resulting in widespread MVFR ceilings across the region. Coastal sites may see some drizzle around sunset time through midnight. Any accumulating precipitation is expected to remain very light, between 0.02-0.03 inches, and may cause a slight reduction in visibility.

Vicinity of SFO, VFR conditions this afternoon with SW moderate winds with strong gusts in excess of 22 kt. Winds will weaken after sunset. As the marine layer deepens to around 2500 feet overnight, MVFR ceilings are expected to impact the terminal as early as 08Z Saturday and persist through 19Z Saturday.

SFO Bridge Approach, SW wind and gusty pattern is similar to SFO. MVFR ceilings will develop slightly after SFO (09-10Z) and dissipate to SCT before SFO does (17-18Z). Will remain patchy through the late morning and become fully VFR by 19Z.

Vicinity of SJC and OAK, VFR paired with moderate breezes this afternoon will begin to weaken after sunset. Gusts around 18 to 20 kts at SJC and OAK. MVFR ceilings will impact OAK first around 07Z Saturday followed by SJC a couple hours later (09Z Saturday). Winds ease overnight before increasing again Saturday morning when the stratus begins to scatter out of their respective areas.

Monterey Bay Terminals, VFR conditions with moderate onshore winds this afternoon with gusts in excess of 20 kts will begin to weaken after sunset. Another round of MVFR ceilings return this evening, impacting SNS first around 03Z and MRY by 05Z Saturday. Medium confidence on the timing of stratus at MRY as it may be intermittent at times. There also might be some light drizzle associated with the marine layer as it comes onshore, similar to this morning, but confidence is too low to include in the TAF.

Marine

(tonight through next Wednesday) Issued at 223 PM PDT Fri Jun 19 2026

Winds will increase becoming fresh to strong out of the west into the early evening hours. Hazardous conditions for small craft are expected across the San Francisco Bay, Suisun Bay, San Pablo Bay and Monterey Bay. Long period southwest swell will persist into the weekend with moderate W/SW winds across the outer waters. Winds will briefly ease Saturday but will increase again across the outer northern water early Sunday into the beginning of next week.

Beaches

Issued at 1245 AM PDT Fri Jun 19 2026

Long period southerly swell at around 15 to 17 seconds will persist through early Sunday as energetic storms in the Southern Hemisphere continue to affect the California coast, especially for south and southwest facing beaches. Hazardous beach conditions are advertised, specifically for moderate to steeply sloped beaches along the Pacific Coast of the North Bay, San Mateo, Santa Cruz counties. A Beach Hazards Statement for Pacific Coast beaches continues through late Saturday night. Be sure to check beach conditions before you head out. Sneaker waves will run up the beach much farther than other waves, potentially catching beachgoers by surprise and resulting in people being swept into the water. Rip currents are strong enough to pull the strongest swimmers away from shore. Swim near a lifeguard if possible. Stay back from the beach, and away from jetties, piers, beachside rocks, and other infrastructure near the water. Never turn your back to the ocean!

Watches, Warnings, Advisories

Ca, Beach Hazards Statement through late Saturday night for CAZ006- 505-509-529-530.

PZ, Small Craft Advisory until 9 PM PDT this evening for Mry Bay-SF Bay N of Bay Bridge.

Small Craft Advisory from 9 PM Saturday to 3 AM PDT Monday for Pt Arena to Pt Reyes 10-60 NM.

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