, Issued at 1230 AM PDT Mon Oct 5 2026 (Today and tonight)
The weak upper level disturbance embedded in the broader scale ridging can be seen on satellite shifting inland overnight. Unfortunately it offers no relief in cooling temperatures and will reinforce offshore flow as it continues to exit east during the day today. A Heat Advisory remains in effect for most of our area through Wednesday night, however the advisory for the immediate coastline from Sonoma County south to Santa Cruz County was allowed to expire on schedule. Todays high temperatures will continue to run 15-25 degrees above normal with overnight lows generally running 10- 20 degrees above normal, offering little to no night time relief to the moderate to major HeatRisk we'll see through Wednesday across the interior. Despite a return of stratus along the coastline, expect the marine layer to continue to hold primarily to the coast today while remaining compressed and fighting fetches of offshore flow.
Follow these tips to avoid heat exhaustion and heatstroke:
* Stay hydrated and drink plenty of fluids. * Wear lightweight, light-colored clothing. * Reduce time spent outdoors or stay in the shade. * Never leave people or pets unattended in vehicles. * Use sunscreen if going to the coast or the pool.
..issued at 1230 AM PDT Mon Oct 5 2026 (Tuesday through Sunday)
The synoptic scale ridging across our region will be reinforced through mid-week in the wake of the weak upper level system to our north exiting east today. Temperatures today through Wednesday will be very similar with little day to day variability for most locations. Another weak upper level system develops offshore for the middle to end of the upcoming work week, and will combine with a more potent disturbance embedded in the polar jet to begin to lower H50 heights by Thursday with a return to more normal temperatures for the end of the week into the weekend, when daytime highs are expected to fall back to or below normal by the weekend.
(12z TAFS) Issued at 435 AM PDT Mon Oct 5 2026
It's VFR except for a slowly and steadily eastward moving shallow layer of low stratus and fog /LIFR/ reaching the coastline. Because the marine layer is compressed to ~ 500 feet, fog may be locally dense with surface visibilities reduced to less than 1/4 mile. The vast area of fog represents cooler air relative to sea surface temperatures; nocturnal radiative cooling through daybreak will help fog /LIFR/ form as well. Nocturnal radiative cooling will also produce light cool air drainage winds in some of the valleys through daybreak. However, there is also a weak onshore 1 mb SFO-SAC pressure gradient, with no sign of offshore wind at Angel Island at this hour, the wind there has been southwesterly around 16 mph. Just away from the shallow marine layer farther inland and at higher elevations it's still warmer (like Sep and Oct can be) by up to 30F greater this morning within the lower level temperature inversion.
Because of the shallow marine layer depth and strength of lower to mid level thermal ridging, inland areas will stay VFR during the 12z TAFs. Along the coast expect fog to mix out by later morning, with potential for low stratus and/or fog /IFR-LIFR/ returning tonight and Tuesday morning.
Vicinity of SFO, VFR. West wind 5 to 15 knots, strongest in the afternoon to mid evening.
SFO Bridge Approach, Similar to SFO.
Monterey Bay Terminals, It's currently VFR, however expect low stratus and/or fog, possibly dense fog /IFR-LIFR/ forming through daybreak. Diurnal warming will mix out the fog later in the morning with VFR from late morning through afternoon. Expect at least patchy low stratus and/or fog /IFR-LIFR/ tonight and Tuesday morning. Light southeast winds shifting to onshore 5 to 15 knots by late morning to early afternoon. Winds decreasing to less than 10 knots and becoming light land breezes again late tonight and Tuesday morning.
(today through Saturday) Issued at 309 AM PDT Mon Oct 5 2026
An extensive low stratus and fog layer is steadily advancing eastward across the coastal waters and will reach much of the coastline during the morning. Fog may be locally dense at times. A gentle to moderate breeze and slight to moderate wave heights persist into midweek. Winds increase and wave heights build, seas becoming rough across the outer waters, Friday into the weekend.
Ca, Heat Advisory until 10 PM PDT Wednesday for CAZ503-504-506-508- 510-512>518.
PZ, None.
