Swell Matrix

Area Forecast Discussion

National Weather Service San Francisco CA

428 am PDT Thu may 7 2026

Short Term

, Issued at 1124 PM PDT Wed May 6 2026 (Tonight through Friday)

Low clouds are building inland from the coast, covering the bays and working their way into some of the interior valleys. Expect chances for pockets of fog overnight, with the strongest chances in the North Bay. Because of the marine layer's influence and the covering of stratus, overnight temperatures look fairly mild woth most areas seeing lows in the 50s and upper 40s. Only far interior valleys and higher peaks will fall further into the 40s.

Thursday will see a slow erosion of the lower cloud cover, keeping certain areas on the cooler side compared to the areas that stay clear. Inland cloud cover will start clearing in the mid morning, however areas around the bays will keep cloud cover into the late morning and early afternoon. The immediate coast looks to keep cloud cover through the day with moderate to breezy winds, making for much cooler highs than the rest of the area. Expect highs around 60 degrees along the immediate coast, then the 60s and 70s for areas more inland, and into the 80s for areas not experiencing the morning cloud cover. A few areas in the far interior portions of Monterey Co look to break 90 degrees.

Thursday night will offer fairly similar conditions to what we're seeing tonight, but with an earlier inland push of coastal stratus. This will lead to low clouds filling around the SF Bay and Monterey Bay in the mid evening and will cause a quicker cool-down. The lower clouds and the marine layer influence look to go slightly farther inland. This wont have too much of an effect in morning lows, but will make some areas a slightly cooler for Friday as they linger into the late morning and early afternoon.

While most areas will see slightly cooler conditions for Friday, a ridge builds to the north,leading to a small increase in temperatures for the interior North Bay. This will get things back

Long Term

..issued at 1124 PM PDT Wed May 6 2026 (Friday night through next Wednesday)

Friday night will continue to see the affects of the building ridge with a compression of the marine layer and a reduction in the overnight inland push of coastal stratus. Cloud cover will still be prevalent along the coast, but will struggle to enter the SF Bay and reach more of the inland areas.

The reduction of marine influence along with the building ridge calls for much more of the inland areas to break into the 80s for Saturday, while the coast sits in the low 60s, and the slightly inland areas stay in the 90s. A few of the more inland areas look to break into the mid 90s.

The reduction of the marine layer and building of the ridge continues into Monday, which looks to be the hottest day of the current forecast. Most of the interior valleys look to break into the 90s with widespread 80s for all but the near-coastal areas seeing the 60s and 70s. A building of a thermal belt will also call for much warmer lows on the higher peaks (60s and a few 70s) and will lead the peaks into the 90s as well from that warm start. Again the hottest area of the CWA looks to be interior Monterey Co, which will have a few spots looking to break 100 degrees.

The longer term forecast shows good cooling for Tuesday, yet things will stay on the warmer side as the ridge begins to flatten and push east. This will call for a slightly more zonal flow, leading to weak onshore winds into the mid week. The national blend of models looks to continue the steady cooling trend in the late week, but the latest batch of long term model updates are hinting more at another ridge building, which will warm things up again in the late week. The current forecast follows the blend, but as things continue to update, more considerations may need to be made for the potential warming trend.

Aviation

(12z TAFS) Issued at 410 AM PDT Thu May 7 2026

The marine layer is back in earnest this morning. Low stratus clouds are filling the valleys and bringing flight condition impacts to all terminals with IFR-LIFR ceilings this morning. The trend today will be typical of a Summer day, with several hours of clearing from late morning through the afternoon, before ceilings return this evening. The 12Z balloon found the marine layer depth and cloud tops to be around 1800 feet.

Vicinity of SFO, Low MVFR-IFR stratus will continue through the morning. The earliest possible clearing time is 17Z, with chances improving steadily through the subsequent couple hours. Onshore winds will be strong this afternoon, with sustained winds up to 20 knots expected. Marine layer stratus will return sometime between 02Z to 09Z. The exact ceiling return time is the most uncertain part of the TAF for now, but it will very likely return at some point this evening.

SFO Bridge Approach, Similar to SFO.

Monterey Bay Terminals, Fully socked in. MRY is reporting ceilings of 100 feet with 4 mile visibility. These very poor conditions are likely temporary, but LIFR-IFR conditions will persist through the early to mid morning hours. Expect gradual improvement around 18Z with clearing around 21Z at MRY, and a quicker clearing timeline at SNS. There is a 20% chance that MRY doesn't clear at all today, but the ceilings will at least lift to MVFR during the afternoon in the worst case scenario.

Marine

(today through Tuesday) Issued at 410 AM PDT Thu May 7 2026

NW winds will increase to a strong breeze by tonight and remain strong through the weekend. Seas will steadily build through the day in response to the stronger winds.

Watches, Warnings, Advisories

Ca, None. PZ, Small Craft Advisory from 9 PM this evening to 3 PM PDT Saturday for Pt Arena to Pt Reyes 0-10 nm.

Small Craft Advisory from 3 AM Friday to 3 PM PDT Saturday for Pigeon Pt to Pt Pinos 0-10 nm-Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 10-60 NM-Pt Reyes to Pigeon Pt 0-10 nm.

Small Craft Advisory from 9 AM this morning to 3 PM PDT Saturday for Pt Pinos to Pt Piedras Blancas 0-10 nm.

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