Marine Weather and Tide Forecast for Livermore, CA

UPDATE
Issued at 856 AM PST Sat Feb 28 2026

The current forecast is on track with water vapor imagery indicating that our shortwave ridging has been replaced with more in the way of upper troughing. The large scale ascent associated with this feature has supported the development of showers and even a few lightning strikes across our offshore marine zones. The primary PV anomaly is anticipated to lift northward this afternoon and this translates to a mostly PoP-free forecast after 00Z Sun until 18Z Sun when our next storm system skirts eastward.
We'll have another look at Sunday's PoPs with the primary forecast package as the trend has been for an increase in rain chances across the North Bay. As noted below, the probability of a tenth of an inch is only about 10% and that represents the higher end amount. These higher end amounts are more probable in the upslope regions of the North Bay and within locations that experience deeper convective elements. We'll continue to examine the thunderstorm potential, particularly given the presence of instability as manifest by the lightning activity that has been observed thus far. More information later this afternoon.

SHORT TERM
Issued at 229 AM PST Sat Feb 28 2026 (Today and Sunday)

The 00Z sounding observed an 850 mb temperature of 15.35 degrees Celsius which is the second highest (16.3 degrees Celsius in 1986)
for the date and time. With a warm air mass in place, well above normal temperatures are expected today. Surface high pressure in the Intermountain West and a coastal trough off the California Coast will generate light offshore flow. So not only will we be warm, but our natural air conditioning (the sea breeze) will be turned off. To limit heat-related impacts, people should increase water intake, reduce time spent outdoors or stay in the shade when the sun is the strongest, and open windows at night and use fans to bring cooler air inside buildings. We will begin to feel the influence of an upper-level low in the Eastern Pacific Ocean today, as alluded to by the high clouds that are beginning to stream in. The first of two embedded shortwaves will swing through the region today, bringing with it a slight (15-25%) chance for rain with embedded thunderstorms possible. The highest probability of occurrence (still low) will be in the North Bay with ensemble members continuing to show little to no accumulation today. The second embedded shortwave will swing through on Sunday, bringing us another chance for rain and thunderstorms. Measurable rainfall (0.01 inches or greater) is now looking likely (60% chance) on Sunday for the North Bay - especially in the higher terrain. If the criteria gets bumped up to a wetting rain (0.10 inches or greater), the areal extent is significantly reduced to only the Mayacamas Mountains and Hills of Western Sonoma County. Thunderstorm chances will remain low (20% or less) through this upper-level low. The three ingredients needed for thunderstorm development are lift, instability, and moisture. While all will be present, they are not expected to overlap favorably in space and/or time. Sensible weather wise, Sunday will be about 10 degrees cooler than today. For locations south of the Golden Gate Bridge, drizzle will be possible along the coast and in the higher terrain.

LONG TERM
Issued at 229 AM PST Sat Feb 28 2026 (Monday through Friday)

The upper-level low will begin to fill as it moves through the region on Monday. As it does so, rain chances will be renewed yet again Monday morning with light rain possible for the North Bay and drizzle possible for coastal and higher terrain locations south of the Golden Gate Bridge. Upper-level shortwave ridging will begin to nose in from the Eastern Pacific Ocean the latter half of Monday.
The pattern will remain progressive with an upper-level shortwave trough on the ridge's heels. There is uncertainty on the location and the evolution of this feature, and to some extent the strength.
It can be discerned though that this pattern will be conducive for warm and dry conditions with offshore flow, especially Wednesday through Friday. Even though we are in Winter with rainfall totals right around normal for this time of year, it's never too soon to think ahead towards "fire season". One side of the fire triangle (fuels) is right around average for this time of year; however, Energy Release Components (ERC), Burning Indices (BI), and 100 hour dead fuel moisture are all expected to be above average by early next week. While fuels are still projected to remain within the "significant spread unlikely" range, this is still something to be made aware of as receptive vegetation will have the potential to burn, especially on any wind-and-terrain aligned starts. As always, exercise fire weather safety no matter the time of year.

AVIATION
(18Z TAFS)
Issued at 1024 AM PST Sat Feb 28 2026

Our first upper trough continues to lift northward and a secondary upper air disturbance will encourage stronger onshore flow as well as an increase in moisture. VFR ceilings will become MVFR and even a window for IFR, especially at North Bay Terminals.
The onset time is tricky and current thinking is that MVFR/IFR will be more probable closer to 12Z Sunday. However, if the secondary upper low moves more quickly to the east, sub-VFR cigs as early as 06Z are more likely. IFR/LIFR is most likely at KSTS and KHAF through the end of the valid TAF cycle, though if the marine layer deepens, cigs may lift quickly, with a non-zero chance that VFR returns prior to 18Z Sunday. Confidence in the cig forecast is greatest in the North Bay, with lesser confidence farther south, where terrain may hinder the advancement of stratus at some locales (e.g., LVK and SJC). Largely terrain driven flow this afternoon and tonight will become more westerly with the approach of the upper low.

Vicinity of SFO...Currently VFR with NE'ly winds. The delayed sea-breeze push is expected closer to 21Z. While confidence has diminished in IFR, forecast soundings/cross-sections do indicate that the initial push of moisture may be low enough such that cigs are below FL010, at least for a few hours around 12Z Sunday. The Sunday AM push is likely to be impacted due to IFR/MVFR. As onshore flow continues, cigs will lift, becoming VFR during the afternoon. If moisture is deeper than anticipated, MVFR may persist longer than advertised. At this time, the potential for SHRA INVOF appears that it'll be after 00Z Monday, but if the upper trough accelerates faster, adjustments to include precip in the 24-30 hour window of the TAF will be needed.

SFO Bridge Approach...Cigs are likely to arrive up to 2 hours after the initial arrival at the terminal.

Monterey Bay Terminals...VFR conditions with a persistent push of onshore flow is expected through tonight. Moderate confidence that our stratus deck will push through around 10-11Z Sunday resulting in IFR conditions. Once it comes through, it is expected to remain IFR through 18Z Sunday at KMRY and potentially closer to 16Z at KSNS. The onshore winds are forecast to be light, largely within the 6 to 8 knot range, with gusts up to 10 knots.



MARINE
(Today through Thursday)
Issued at 856 AM PST Sat Feb 28 2026

Average to long northwesterly swell will continue through the weekend before wave heights and swell periods both decrease.
Rougher seas should be anticipated in and around shower or thunderstorm activity. The risk for this activity will continue through Sunday. Seas continue to abate until about mid-week.
Thereafter, conditions will deteriorate as a series of stout strong systems usher in Gale Force wind gusts and steep seas over 12 feet.

CLIMATE
Issued at 1116 PM PST Fri Feb 27 2026

The following are the record high temperatures at the long term sites for Saturday, Feb 28th.

Location Feb 28th Record High

Santa Rosa 93 in 1923 San Rafael 78 in 2025 Kentfield 78 in 1929, 1923 Napa 81 in 1929 Richmond 77 in 1986 Livermore 82 in 2022 San Francisco 76 in 1992, 1986 SFO Airport 73 in 1959 Redwood City 77 in 2025 Half Moon Bay 74 in 1954 Oakland Museum 75 in 2025 San Jose 77 in 2025, 1926 Salinas Airport 81 in 2022

MTR WATCHES/WARNINGS/ADVISORIES
CA...None.
PZ...None.