textproduct: San Francisco Bay Area

KEY MESSAGES

Updated at 1010 AM PDT Fri Mar 27 2026

- Above normal temperatures continue through the weekend

- Beneficial rain possible next week

SHORT TERM

Issued at 1010 AM PDT Fri Mar 27 2026 (This afternoon through Saturday)

Despite the high clouds moving in from the south, max temperatures today will challenge daily records. The morning sounding found 850 mb temperatures of 16.75 C, and a 500 mb height of 5800m. Those benchmarks are both between the 90th percentile and daily max for this date. In addition to the background atmospheric heat content, there are offshore winds helping keep the surface warm and dry via downslope flow and adiabatic heating. As such, a couple daily records may fall today, but not nearly as widespread or historic as last week when the 850 mb temperate reached a ridiculous 22 C. Despite the possible records, the high clouds and gentle breeze should help it feel pleasant for most this afternoon.

By Saturday the surface high pressure over the Rockies will be replaced by low pressure moving in from Canada. This will either neutralize the offshore gradient or flip it to weak onshore flow, depending on the strength of the low pressure. This change opens the door for a shallow marine layer to creep in, bringing low clouds and possibly morning fog to the coast and adjacent low- lying areas. The onshore winds will also suppress the temperatures a bit, but the warm low-middle atmosphere will ensure temperatures stay well above normal.

LONG TERM

Issued at 1010 AM PDT Fri Mar 27 2026 (Saturday night through next Thursday)

After a minor cool-down Saturday, near record warmth returns on Sunday. Some light offshore flow is likely to return, but the high clouds that are suppressing temperatures today will be thinner and more scattered. Inland areas should reach the mid 80s, with 70s along the coast. Monday is a transition day before temperatures finally return to normal next week. Ensemble clusters agree that a trough will move in and usher out the persistent ridge. The depth of this trough is still in question, with some solutions keeping the majority of the precipitation in the Pacific Northwest and others digging down to central California. So we know the temperatures will drop, but the precipitation amount remains in question. Our official forecast has around 1/4" in the interior and up to 1" in the coastal mountains from Tuesday through Wednesday. The dry scenario is more like a trace in the low lands and a few hundredths in the coastal mountains, while the wet scenario is more like 3/4" inland and 2-3 inches in the coastal mountains. The reality can be either of these, or of course somewhere in the middle. There is even a 20% chance that we fall outside of that wide range, to one side or the other. This just highlights the remaining uncertainty with this system. Don't bank on any deterministic forecast just yet. Whatever happens mid week, it does look like the pattern will stabilize late week before another ridge builds in the following week.

AVIATION

(00Z TAFS) Issued at 422 PM PDT Fri Mar 27 2026

VFR with high clouds across the region. Breezy onshore winds continue across the coastal regions, with the lingering offshore push keeping winds light in the interior. Winds turn light overnight with a moderate-high confidence of a surge of stratus coming into the immediate coastal regions after midnight, with some intrusion into the Sonoma County valleys, East Bay, and the Monterey Bay region. Patchy fog is possible in the coastal regions and the Sonoma County valleys. High resolution models have fog developing around 09- 10Z. Besides STS, have refashioned the previous TEMPO groups into prevailing forecasts for fog, but this is a low to moderate confidence forecast at this time. Stratus retreats and lifts through Saturday morning, with patchy stratus persisting at the immediate coast while the onshore winds resume.

Vicinity of SFO... VFR with thin high clouds through the TAF period. Breezy west-northwest winds continue through the evening hours. Winds gradually diminish in the late evening with light winds Saturday morning, before the breezy west-northwest winds resume during the afternoon. Very low confidence of stratus impacts to night at the terminal, with moderate confidence of impacts to the Berkeley area and lower confidence at OAK.

SFO Bridge Approach... Similar to SFO.

Monterey Bay Terminals... VFR conditions with breezy northwest winds through the rest of the day. Moderate to high confidence that a surge of stratus will impact the region after midnight with patchy fog likely. Most recent high resolution model output has the fog arriving around 09-10Z. Have refashioned the previous TEMPO groups into prevailing forecasts for fog, but this is a low to moderate confidence forecast at this time. Saturday morning, ceilings lift and later dissipate as breezy northwest winds resume.

MARINE

(Tonight through next Wednesday) Issued at 422 PM PDT Fri Mar 27 2026

High pressure over the Eastern Pacific continues to dominate the pattern, producing a moderate to fresh NW breeze and moderate seas through the weekend. Conditions will be slightly heavier on Saturday across the NW waters, with a fresh to strong NW breeze and rough seas to 8 ft.

FIRE WEATHER

Issued at 1010 AM PDT Fri Mar 27 2026

In addition to the heat, the air is also dry thanks to some offshore winds supported by the gradient between high pressure over the Rockies and a thermal trough over the coast. The SFO-WMC gradient has been around -10 mb for the last 12 hours. Winds were gusting to 30-45 mph across higher elevations of the North and East Bay, enhanced by some mountain wave activity. The relative humidity in these areas was in the teens overnight, which is when you would typically expect the highest RH of the day. The sounding found an incredibly dry pocket of air between 850 and 700 mb, where the average RH is only 2%. The combined hot, dry, and windy conditions are more than enough to reach Red Flag criteria in the North and East Bay mountains today, but we still need the annual grasses to cure before that's an option.

Typically the grass cures and turns brown in the Summer, but this year is ahead of schedule. Downtown San Francisco is currently reporting the warmest March on record (by a healthy 1.5F in terms of average temperature through March 26th) and the driest March since 1923 (Only 0.06" of rain so far, normal for March is 3.15"). To get a sense of the live fuel moisture I compared historical polar orbiting satellite images from past years (search "NASA Worldview" to see for yourself). We are somewhere between a normal April and May in terms of brownness. For dead fuel moisture it's even more stark. The Energy Release Components are setting records across the cwa, with the Mid Coast to Mendocino ERC near the average for early July, and Diablo-Santa Cruz near the average for mid-July. The Bay Area Marine ERC is actually above the average for any time of year, and even crossed the annualized 97th percentile. While the hills still have more green than brown and we're not expecting large wildfires anytime soon, the antecedent conditions are set up for an active year.

CLIMATE

Issued at 301 AM PDT Fri Mar 27 2026

Here are the record high temperatures at the long term sites for March 27th and March 29th.

Location March 27th March 29th

Santa Rosa 87 in 1930 86 in 2018 San Rafael 82 in 1969, 1951 85 in 2018 Kentfield 90 in 1923 84 in 1935 Napa 86 in 1930 83 in 2018, 1968 Richmond 82 in 1952 79 in 1968 Livermore 82 in 1969, 1930 85 in 2015 San Francisco 84 in 1923 81 in 2018 SFO Airport 77 in 2021, 1986 81 in 2018 Redwood City 83 in 1969 85 in 2018, 1968 Half Moon Bay 76 in 1952 77 in 2004 Oakland 79 in 1986 79 in 2003 San Jose 85 in 1923 82 in 2018 Salinas Airport 80 in 1969, 1952 86 in 2018

MTR WATCHES/WARNINGS/ADVISORIES

CA...None. PZ...Small Craft Advisory from 9 PM this evening to 3 AM PDT Sunday for Pt Arena to Pt Reyes 10-60 NM.