textproduct: San Francisco Bay Area

KEY MESSAGES

Updated at 1230 AM PDT Sun Jul 12 2026

- Warmer and drier conditions continue through midweek with Moderate HeatRisk returning across the region

- Coastal Flood Advisory for up to 1.7 feet of inundation above ground level is possible in low-lying areas near shorelines and tidal waterways

- Potential for thunderstorms and elevated fire weather concerns continue today and tomorrow

UPDATE

Issued at 922 AM PDT Sun Jul 12 2026

The forecast is on track this morning. Satellite and radar show high clouds and elevated showers over the region. A few locations have reported light rain showers, otherwise webcams have shown more virga.

SHORT TERM

Issued at 1230 AM PDT Sun Jul 12 2026 (Today and tonight)

Monsoonal moisture has started to make its way into the Bay Area and Central Coast. ACARS soundings all show a distinct moistening of the mid to upper levels of the atmosphere at MRY, SJC, SFO, and OAK. This correlates with the influx of mid and high level clouds moving over the region. Radar currently (as of midnight) shows a few showers moving into the coastal waters and across the interior Central Coast. NBM guidance does not show showers reaching the area until late Sunday morning. This increases confidence in the high resolution models (HRRR, NAM) that have consistently showed showers starting Saturday night into Sunday morning before becoming more widespread Sunday into Monday. NBM guidance shows a 5% chance of scattered thunderstorms on Sunday with high resolution guidance suggesting thunderstorm potential will increase starting early this morning. The overall confidence that high based thunderstorms (compared to high based showers) will develop today and tomorrow remains low given a lack of forecast instability in the models. The NAM shows the most instability across the region but keeps it limited to a few hundred J/kg of MUCAPE. While the overall thunderstorm risk is low, that does not mean we won't see any thunderstorms develop today or tomorrow. It often takes just a few hundred J/kg of MUCAPE for a thunderstorm to develop here. This is a low probability, high impact scenario wherein if a thunderstorm develops, fire starts will be more likely given how dry the fuels are. Another aspect of this is how much precipitation will reach the surface. Given the high based nature of these storms any precipitation that falls is likely to evaporate before it reaches the ground (virga). Models do support some light rain making it to the ground but this peaks at a few hundredths of an inch. To sum it up, shower activity associated with the monsoonal moisture surge will increase over the next day and a low potential for dry thunderstorms to develop remains on the table.

Temperatures remain in the upper 80s to low 90s across the interior today with the far interior Central Coast peaking in the upper 90s to low 100s. Coastal areas and the SF Bay shoreline will see temperatures peaking in the 70s to low 80s. Conditions may feel more humid during the day due to the influx of monsoonal moisture across the region. Temperatures drop into the 60s across the lower elevations Sunday night and remain in the 70s across the higher elevations. Widespread Moderate HeatRisk is expected across the higher elevations today with patchy Moderate HeatRisk across the urban portions of the Bay Area.

LONG TERM

Issued at 1230 AM PDT Sun Jul 12 2026 (Monday through Saturday)

Beyond Monday's thunderstorm chances (discussed in Short Term), shower and thunderstorm potential will dissipate Tuesday with most models suggesting the monsoonal moisture surge will diminish across our CWA. ECMWF guidance suggests enough moisture may linger during the day on Tuesday to see an isolated shower or two across the higher terrain but confidence is low in that scenario. Another round of monsoonal moisture, potentially bringing showers back to the region, is possible Friday into next weekend. The forecast remains in flux with regards to a second moisture surge so stay up to date on the forecast this week.

Outside of shower potential, upper level ridging will continue to dominate the western United States with the center of the high located over the Intermountain West. Temperatures warm into the upper 80s to 90s across the interior with low 100s possible across the usual hotspots (far interior East Bay, interior Central Coast) Tuesday and Wednesday. Coastal areas will stay in the 60s to 70s with low 80s possible along the SF Bay shoreline. Widespread Moderate HeatRisk is expected across the higher elevations and most of the interior Bay Area. If you are spending significant periods of time outdoors, make sure to listen to your body, take breaks in the shade, and drink plenty of water. Cooler temperatures return Thursday into the weekend as upper level ridging weakens and shifts eastward while a deep upper level trough pushes into the PNW.&&

AVIATION

(18Z TAFS) Issued at 1203 PM PDT Sun Jul 12 2026

Monsoonal moisture will continue to surge into the region, leading to high clouds, elevated rain showers, and VFR conditions for the main terminals. Surrounding the sites, in the terrain, we can expect to see bubbling cumulus and elevated convection, which could produce brief pockets of rain and gusty winds. Should enough convective ingredients come together, which is currently sitting at a less than 10% chance, we could get an isolated thunderstorm or two.

Vicinity of SFO...Mid to high based clouds and elevated showers will continue to pass over the region. Light winds have started to shift and will gradually shift o the southwest for a brief period this afternoon. The seabreeze will return bringing 10-15kt winds before ease a bit overnight. Some model guidance shows a subtle hint of a shallow marine layer late tonight and into early Monday morning. A few low clouds could flirt around the Bay, but VFR conditions should prevail.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Light winds, high clouds, and elevated showers will pass over the region today. A mix of light rain showers and virga will be possible, with most locations remaining dry until the profile moistens up. VFR conditions are expected; however, similar to the SF Bay, there is subtle hint for stratus late tonight and into tomorrow morning. Opted to hint at it rather than socking terminals in.

MARINE

(Today through Friday) Issued at 922 AM PDT Sun Jul 12 2026

Moderate to fresh northerly winds are outer waters leading to hazardous conditions. Otherwise, expect light to moderate north- northwest winds with moderate northwest swell. Winds and seas build by the middle of next week.

FIRE WEATHER

Issued at 439 AM PDT Sun Jul 12 2026

Warm and dry conditions persist through much of the upcoming week, especially away from the coastal marine influences which are forecast to persist. This will increase fire weather concerns as fuels rapidly dry out due to low humidities. Fire weather concerns further increase later tonight into Monday as a surge of monsoonal moisture advects northward around the western periphery of the high pressure over the Desert Southwest and Intermountain West. If thunderstorms are able to develop, dry lightning and gusty, erratic outflow winds would be the main hazards. The limiting factor is the lack of instability over our region those days. Thus, we will continue to closely monitor these conditions through the weekend. Given the combination of the potential for dry lightning and rapidly drying fuels, it is important to stay up to date on the forecast as it evolves.

MTR WATCHES/WARNINGS/ADVISORIES

CA...Coastal Flood Advisory until 4 AM PDT Thursday for CAZ006-506- 508.

Coastal Flood Advisory until 4 AM PDT Wednesday for CAZ505-509- 529-530.

PZ...Small Craft Advisory until 3 PM PDT Wednesday for Pt Arena to Pt Reyes 10-60 NM.