, Issued at 1229 PM PDT Sat Sep 19 2026 (This evening through Sunday night)
The marine layer is around 1,500 feet deep and the morning clouds have pulled back to the coast. There is a weak offshore gradient (SFO-WMC -3mb) that caused some moderate NE winds across the North Bay and East Bay mountains early this morning. The sea breeze is now taking over, flipping winds back onshore as the mesoscale gradient weakens. A 500 mb short wave ridge axis will move over the Bay Area this afternoon. This building ridge is causing subsidence and warmer conditions in the lower atmosphere. Surface temperatures are around 5 degrees warmer than this time yesterday outside of the cloudy coast. That puts us right around normal for this time of year.
A weak cut-off low will start to move in from the west Sunday. This will reverse the warming trend and bring temperatures around 5-10 degrees below normal again. It will also encourage the the marine layer to expand a bit.
..issued at 1229 PM PDT Sat Sep 19 2026 (Monday through next Friday)
The cut-off low will move overhead Monday. This will keep the cooler temperatures in place, deepen the marine layer, and may bring some morning drizzle to the coast and windward slopes. The ECMWF shows some decent 850 mb vorticity, which will help create the lift necessary to form drizzle drops within the deeper cloud layer. These are still tiny drizzle drops though, so any accumulation will be very light.
By Tuesday we will be on the backside of the low and a more substantial warming trend will begin. A relatively low-amplitude 500 mb ridge will build through the middle of the week, but 850 temperatures will climb to 20 to 23C by Wednesday and Thursday. That range is approximately the 75th to 95th percentile for this time of year. Our current forecast has near normal temperatures across the interior Tuesday, steadily building to 10 to 15 degrees above normal by Thursday. With no sign of strong offshore winds, a shallow marine layer will likely survive this warm-up, at least through Wednesday. Heat Advisories are possible, but we're getting to the time of year where the nights are just as long as the days, which really helps dull the accumulating impacts.
The ridge will start to break down Friday as a 500 mb trough moves over the Pacific Northwest. This will bring temperatures back down. There's still no real chance for rain until the following week.
(18z TAFS) Issued at 1112 AM PDT Sat Sep 19 2026
Marine layer around 1000 feet with low cigs rapidly retreating towards the coast. Expect all terminals to be VFR by 19z except KMRY and KHAF. Low cloud deck to surge back inland tonight as next shortwave trough approaches with slight deepening of the marine layer overnight into Sunday.
Vicinity of SFO, Ceilings have cleared with west winds this afternoon/evening. Low cigs to return after 05z tonight and lasting at least through 18z Sunday.
SFO Bridge Approach, Approach is clear and will stay that way at least through 06z tonight.
Monterey Bay Terminals, Low cigs to pull back to the coast by 19z. Low cigs may linger near KMRY for much of the day and then spread back inland by 02z and down the Salinas Valley.
(today through Thursday) Issued at 418 AM PDT Sat Sep 19 2026
Moderate to fresh northwest winds persist through the weekend. Strong gusts up to 30 kt are possible across the northern coastal waters, the Big Sur coastal jet region, and Monterey Bay through the day. Winds briefly diminish across the southern coastal waters this morning, but increase again to fresh by the afternoon. Slight to moderate wind driven seas prevail this weekend and steadily build to rough early next week.
Ca, None. PZ, Small Craft Advisory until 9 AM PDT Sunday for Pt Arena to Pt Reyes 0-10 nm.
Small Craft Advisory until 3 AM PDT Sunday for Pigeon Pt to Pt Pinos 0-10 nm.
Small Craft Advisory from 3 PM to 9 PM PDT Sunday for Pigeon Pt to Pt Pinos 0-10 nm.
Small Craft Advisory until 3 AM PDT Monday for Pt Pinos to Pt Piedras Blancas 0-10 nm.
Small Craft Advisory until 9 AM PDT Monday for Pt Arena to Pt Reyes 10-60 NM.
Small Craft Advisory until 3 AM PDT Monday for Pigeon Pt to Pt Pinos 10-60 NM.
