textproduct: San Francisco Bay Area

KEY MESSAGES

Updated at 1129 PM PDT Mon Jul 27 2026

- Breezy onshore winds expected each afternoon and evening through early midweek

- Gradual warming starting midweek, with Moderate HeatRisk for interior locations through the weekend

- Elevated fire weather threat across the interior North and East Bay, Diablo and Santa Lucia Ranges this week

- Hazardous beach conditions at the Pacific Coast with an increased risk for sneaker waves and rip currents through the end of the week

UPDATE

Issued at 930 AM PDT Tue Jul 28 2026

Water vapor imagery shows a relatively deep trough of low pressure situated along the West Coast this morning, with a couple of embedded short waves within this trough. The multiple water vapor channels also show very dry air situated over California this morning at the various levels. As a result, there is no cloud cover over the state, with the exception of the marine layer along the immediate coast. The 12z KOAK sounding shows that the marine layer is approximately 1700 feet deep, with an impressive inversion of nearly 12 deg above the marine layer. This warmer layer could be seen in some of the thermal belted areas, where overnight low temperatures stayed in the mid 60s to lower 70s, such as Highlands Peak. Meanwhile, the drier air over the region allow for some decent radiative cooling last night away from the coast, with most locations staring off in the upper 40s to 50s. The marine layer helped moderate some of the coastal locations, so temperatures were more in the mid 50s to lower 60s.

At this time, temperatures are running similar to this time yesterday, and expect this trend to continue through the day. Gusty onshore winds will also develop through the day, and this will help continue to moderate temperatures along the coast, while inland areas will still be seasonally warm. Current forecast looks on track, with no updates are planned for the forecast at this time. Palmer

SHORT TERM

Issued at 1221 AM PDT Tue Jul 28 2026 (Today and tonight)

If you read the evening AFD update micro-climates were highlighted. Seems fitting to kick off this AFD with another micro-climate highlight. If one looks at the overnight satellite imagery they'll notice only patchy stratus developing. I do expect more by morning, but patchy for now. So why is it patchy, pockets of offshore flow most notably over the N Bay and along the Big Sur coast. Offshore flow is a drying and warming wind for our region. Taking a closer look at Big Sur there are two sensors called Highlands Peak. It's close to midnight and both are reporting temperatures near 80 degrees. N to NE flow leads to compressional warming as the air descends the Santa Lucias, hence the warm temperatures.

Tuesday will be another pleasant day weather wise most areas. The longwave pattern continues to advertise broad upper level troughing just offshore and upper level ridging to the SE. Similar to Monday we'll see a large spread of temps from the coast to the interior. Onshore flow will keep coast/bays in check with highs in the 60s/70s. Farther inland with marine layer influence will see much warmer temperatures with highs in the upper 80s to near 100.

Given the temperature contrast expect another round of breezy afternoon winds in the valleys and inland gaps/passes.

Tuesday night the upper level trough begins to ease with upper level ridging building in from the east. As such, a more stable marine layer will develop with slightly better stratus coverage. Above the marine layer temperatures will be on the milder side.

LONG TERM

Issued at 1221 AM PDT Tue Jul 28 2026 (Wednesday through Monday)

Wednesday will be a transition day as the longwave pattern shifts from nearby trough to a building ridge. It should be noted the building ridge from the east brought very dangerous heat to the Desert SW. Not expecting that here, but a marked warm up nonetheless. Expect an initial jump in temps of 3-5 degrees from Tuesday to Wednesday. Still seeing some night/morning marine stratus given lingering onshore flow. Additionally, we will continue to see the large temp spread from the coast to the interior.

Thursday through Monday - The heat dial gets turned up each day and peaks over the weekend before moderating early next week. The very warm upper level ridge to the east will overspread the region for much of the long term. Projected 850mb temps will be in the mid to upper 20s, which when fully mixed will easily support temps in the 105-110 range. However, onshore flow remains at the surface. Therefore, the fullest potential of the airmass will only be realized across the interior. That's the key to keeping the coastal areas and bays in check temp-wise - onshore flow. Some guidance does show periods of easing onshore flow and that has bust potential written all over it with coastal areas ending up warmer than forecast. Confidence isn't high enough to fully buy that solution just yet. Much higher confidence exists for interior locations to experience triple digit heat. Given the very mild airmass thermal belts will be very active too with minor relief in the hills overnight. Could easily see temps staying in the upper 60s to mid 70s in the hills. Therefore, as daytime temperatures increase and less nighttime relief is observed overall HeatRisk increases. While most areas without any marine influence will be moderate HeatRisk from Thursday through early next week there will be pockets of Major to Extreme for interior Monterey/San Benito. As the weekend forecast becomes more clear will need to take a look to see if a heat advisory is needed.

Longer range guidance diverges on extent of the heat, but some guidance keep the heat going for much of next week.

AVIATION

(18Z TAFS) Issued at 1042 AM PDT Tue Jul 28 2026

VFR is imminent for the Bay Area terminals with KHAF potentially bouncing back and forth through the TAF period at MVFR/IFR. A local circulation will maintain MVFR/IFR ceilings at KMRY through at least 19z with clearing expected by 20z. The relatively unorganized marine layer continues to be a challenge to predict extent and timing. North Bay terminals if they see stratus ceilings it may not be until around sunrise Wednesday.

Vicinity of SFO...As mentioned above, stratus clearing is imminent with VFR persisting through at least sunset. Hi-res guidance suggests the potential for stratus spilling over and through the San Bruno gap to KSFO as early as sunset with more confidence in development after midnight, with earlier clearing time as warmer temperatures begin to mix down by Wednesday morning.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Satellite trends indicate a local circulation maintaining MVFR/IFR ceilings as late as 20z at KMRY with KSNS at VFR and will continue through the remainder of the afternoon and early evening. IFR/LIFR ceilings are possible late in the TAF period.

MARINE

(Today through Sunday) Issued at 1042 AM PDT Tue Jul 28 2026

Northwest breezes will continue to be fresh to strong through the remainder of the week into the weekend. Coastal jet regions along the Big Sur and Point Reyes will likely see gale force gusts with moderate seas becoming rough through the middle of the week as northwest winds increase. Tropical activity will continue to produce long period swell along our coastal waters into the weekend.

FIRE WEATHER

Issued at 152 PM PDT Mon Jul 27 2026

The elevated fire weather threat will persist across portions of the area through mid-week. Overnight RH recovery will remain moderate at locations at or above 2,000 feet with values around 40 to 50 percent. This will be particularly true across the Mayacamas, highest peaks of the East Bay Hills, the Diablo Range, Santa Cruz Mountains, Santa Lucia and Gabilan Ranges. Nocturnal drying (rapid decrease in RH through the pre-dawn hours) may also transpire which will increase the burn period or time in which fire behavior may remain active. Afternoon RH will remain critically dry with values between 20 and 40 percent, with far southern portions of the interior Central Coast potentially seeing min RH near 10 percent. Energy Release Components (ERC) are projected to climb above the 95th percentile across the interior Central Coast. Individuals across the area are advised to avoid activities that may spark a fire. Fire crews are urged to exercise extra caution when executing any prescribed burns, especially where fuels, topography, and weather align.

BEACHES

Issued at 145 PM PDT Sun Jul 26 2026

Distant tropical cyclones in the Eastern Pacific will continue to generate 16-18 second (long-period) southwesterly swell which has reached the coastline of the San Francisco Bay Area and Central Coast. As such, sneaker waves and strong rip currents are the primary concerns. Breaking waves can reach up to 12 feet along some south and southwest facing beaches and break points, such as Santa Cruz, Pacifica, and parts of Stinson or Ocean Beach. This can be particularly surprising when wave heights increase suddenly after a period of seemingly tranquil wave action. In fact, sneaker waves can have 20+ minutes in between the larger sets (breaking waves) with significant "flat/calm looking" times between them. Due to the long period, sneaker waves are powerful and can catch beachgoers by surprise, resulting in people and pets being swept into the cold, turbulent ocean. Rip currents are strong enough to pull even the strongest swimmers away from shore. Check marine conditions before you head out! Swim near a lifeguard, if possible. Maintain a safe distance from the water, and stay away from jetties, piers, beachside rocks, and other waterside infrastructure. Never turn your back to the ocean and if you have small children or pets at the beach, please keep an eye on them. Hazardous beach conditions are anticipated to persist through Saturday afternoon.

MTR WATCHES/WARNINGS/ADVISORIES

CA...Beach Hazards Statement through Saturday afternoon for CAZ006- 505-509-529-530.

PZ...Small Craft Advisory from 3 PM this afternoon to 9 PM PDT this evening for Mry Bay-SF Bay N of Bay Bridge.

Small Craft Advisory until 3 PM PDT Thursday for Pigeon Pt to Pt Pinos 0-10 nm-Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 0-10 nm-Pt Arena to Pt Reyes 10-60 NM-Pt Reyes to Pigeon Pt 0-10 nm.

Gale Warning until 3 PM PDT Wednesday for Pt Pinos to Pt Piedras Blancas 0-10 nm.