Issued at 927 AM PDT Tue Sep 8 2026
Want to emphasize that today will begin a warm-up that will peak tomorrow, then moderate somewhat on Thursday with temperatures closer to normal by Friday into the weekend. Even though todays heat may not reach the level or extent necessary for an advisory, it will still feel warmer than normal across much of our area, including much our coastal areas that are experiencing a weak fetch of offshore flow. Another factor adding to the heat concerns tomorrow and Thursday, is the amount of moisture advecting north with the remnants of Marie. Not only will we see higher temperatures, we'll see less relief overnight with the higher dewpoints and higher relative humidity levels during peak heating Wednesday and Thursday, further complicating heat impacts. Remember to never leave people or pets in the car, take plenty of breaks and seek shade/AC shelter if working outside and drink plenty of people.
, Issued at 1151 PM PDT Mon Sep 7 2026 (Tonight through Wednesday)
24 hour trends are warmer and drier. Already a warming trend is underway with increasing thermal and height ridging aloft. Any marine layer influence is confined to within a few hundred feet of sea level with only a few patches of fog along the Big Sur coast at the moment.
The large scale pattern shift to warmer/hotter temperatures involves both the retrogression (westward motion) of the subtropical ridge over the central U.S. and the eventual merging of tropical energy and moisture from steadily decaying TS Marie and a cut-off low far to our west (also forecast to retrogress). Strengthening 500 mb heights, large scale compression and the Sep Sun angle will raise temperatures up further Tuesday, peaking well above normal both Wednesday and Thursday. A little bit of a wildcard to this week's pattern is the northward intrusion of tropical moisture including some warm air advection (far from decaying TS Marie) which will be west of the 500 mb ridge axis. Higher to much higher precipitable water will arrive here, model forecasts are still showing near 1.40" in the Bay Area mid-week, near the max moving average for Oakland upper air early-mid Sep climatology. Mid and high clouds will increase, but we don't really know quite yet with high confidence how well the models may or may not be handling mid-level convective potential (mucape) with disagreement among various output from e.g. from the HRRR and GFS. Good to see the GFS shows very minimal to no mucape anyhow. Also, with hotter surface temperatures (greater internal energy) air parcels will stay capped as long as the atmosphere is stable.
Hot temperatures for this week are not quite in reach of long term record highs at this point, except Half Moon Bay may get close if there's no shallow sea breeze mid-week as an offset to the temperature. Will continue to monitor.
A Heat Advisory is in effect for the entire forecast area from 10 AM Wednesday to 10 PM Thursday. We've had a nice 10 to 11 day run of below normal temperatures (due to a large scale trough), especially inland, so the sudden reversal in temperatures will be noticeable if not already. With widespread moderate to major HeatRisk, this affects most individuals sensitive to heat, especially those without effective cooling and/or adequate hydration. Please stay out of direct sunlight, and stay properly hydrated. Hot conditions can cause heat illnesses.
Also, minor coastal flooding is likely within a small window of time of about 1 hour nearest high tide Tuesday (possibly Wednesday as well) for bayshore locations of Marin County. Impacts will include minor flooding of the lowest lying areas directly along the shoreline. At the San Francisco tidal gauge, high tide is expected to be 1 ft above normal at 9:59 PM 9/8. At this time we are messaging it here and will include messaging in social media vs issuing a coastal flood advisory for Tuesday.
The Beach Hazards Statement was allowed to expire.
..issued at 1151 PM PDT Mon Sep 7 2026 (Wednesday night through next Monday)
Well above normal hot weather continues Thursday. Thereafter northwest winds and a gradual weakening of the 500 mb ridge will bring a cooling trend for late in the week and weekend. Daytime highs will cool back to near normal Friday, then possibly a few degrees below normal for the upcoming weekend. Late week weather will be dry with the mid-latitude pattern settling back in.
(18z TAFS) Issued at 958 AM PDT Tue Sep 8 2026
Currently VFR at all terminals with stratus along the Big Sur Coast and high clouds streaming in from the southwest. High confidence in VFR through the TAF period, the only exception would be if an eddy formed in the Monterey Bay or stratus developed off the San Francisco Peninsula Coast. If clouds are able to form, ceilings and visibilities would be LIFR. Diurnal winds will prevail with a later than normal arrival of the sea breeze in the afternoon. Winds will be light and likely variable overnight, favoring terrain.
Vicinity of SFO, Currently VFR with light northeasterly flow. High confidence in VFR through the TAF period. Diurnal winds will prevail with a later than normal arrival of the sea breeze this afternoon. Winds overnight may be light and variable, but will likely favor a northeasterly direction.
SFO Bridge Approach, Similar to SFO.
Monterey Bay Terminals, Currently VFR with northwesterly flow at MRY and VFR with drainage flow at SNS. Moderate to high confidence in VFR prevailing through the TAF period, only exception would be if an eddy is able to develop within the Bay. Diurnal winds will prevail with a later than normal arrival of the sea breeze this afternoon with drainage winds tonight.
(today through Sunday) Issued at 927 AM PDT Tue Sep 8 2026
A gentle to moderate northwesterly breeze will prevail through Wednesday, increasing to become fresh to strong Thursday afternoon into the weekend. Slight to moderate seas will prevail, building to become rough in the outer waters Friday into Saturday.
Ca, Coastal Flood Advisory from 8 PM this evening to 1 AM PDT Thursday for CAZ006-506-508-529-530.
Heat Advisory from 10 AM Wednesday to 10 PM PDT Thursday for CAZ006-502>506-508>510-512>518-528>530.
PZ, None.
