, Issued at 138 PM PDT Tue May 19 2026 (This evening through Wednesday)
Winds have eased across the region with most sites currently reporting light offshore winds under 10 mph. Breezy, onshore afternoon winds are likely along the coast and within mountain gaps/passes. Not too much change to the overall synoptic pattern, broad upper level troughing continues over the western United States with an area of ridging and surface high pressure to our west over the Pacific. The center of the upper level trough continues to progress eastward with the surface pressure gradient becoming more relaxed, allowing wind speeds to diminish overall. The marine layer continues to be mixed out thanks to high pressure offshore which is allowing warmer temperatures to spread across the region. High temperatures will be seasonably warm today and again tomorrow with interior highs in the 80s to possibly the low 90s and coastal highs in the 60s to 70s. Critically dry conditions continue across the interior with the majority of stations reporting RH values in the 10s to 20s. Not much relief from drier conditions has been observed overnight with most sites only seeing overnight humidity recoveries to around 20-30%. This same pattern is expected to continue again on Wednesday with no real relief until the marine layer redevelops late week into the weekend. Fire weather concerns thus remain elevated given the critically dry conditions across the interior. If you are participating in any outdoor activities involving sparks or flame, exercise caution and be aware that fine fuels are very flammable at this time.
..issued at 138 PM PDT Tue May 19 2026 (Wednesday night through next Monday)
The general pattern remains the same through Thursday with high temperatures in the 80s to low 90s across the interior, 60s to 70s along the coast, diurnally breezy winds, and critically dry daytime conditions across the interior. A gradual pattern change will begin Thursday into Friday, becoming more noticeable over the weekend, as high pressure weakens, shifting west, and broad troughing dominates the West Coast. Winds will generally shift onshore again by Friday with a shallow marine layer redeveloping. High temperatures will generally drop into the 70s across the interior and 70s to mid 80s across the interior Central Coast while coastal highs stay in the 50s to 60s. As the marine layer redevelops, we will see improving humidity values across the interior which will reduce our overall fire weather concerns. Initially the marine layer will be around 500 ft Thursday into Friday but is expected to deepen to around 1000 ft by the weekend. Diurnally breezy afternoon/evening winds continue with breezier winds along the coast and in mountain gaps/passes.
The initial NBM forecast shows temperatures warming back into the 80s by early next week. The caveat to this is that models are split between upper level ridging and upper level troughing developing over the West Coast towards the end of May. If ridging is able to develop, warmer temperatures are likely to round out the month but if troughing is able to develop then slightly cooler temperatures are more likely. In the troughing scenario, there is the possibility of some light rain but the more likely setup is a deep marine layer and coastal drizzle.
(00z TAFS) Issued at 421 PM PDT Tue May 19 2026
Currently VFR at all terminals. Moderate to high confidence in VFR and diurnal winds prevailing through the TAF period. Winds may become calm and/or light and variable overnight. Low to moderate (up to 40%) chance of sub-VFR conditions developing at terminals tonight with the best chances between 12Z and 16Z. Coastal terminals will be at greatest risk with risk decreasing for bayshore and interior terminals, respectively. To even get there, it will have to either be advected or dew points need to increase, a lot. The question will be if this can happen before sunrise. If it can't, the probability of occurrence becomes even less.
Vicinity of SFO, Currently VFR with westerly flow. Moderate to high confidence in VFR and diurnal winds prevailing through the TAF period. Low probability for sub-VFR conditions to develop at the terminal with the compressed (LIFR-IFR) marine layer unable to penetrate through the San Bruno Gap. Reasonable worst case scenario is stratus sneaks through the Golden Gate Gap and brings FEW/SCT to the north side of the terminal.
SFO Bridge Approach, The San Mateo Bridge Approach has a lower probability of sub-VFR conditions.
Monterey Bay Terminals, Currently VFR with northwesterly flow at both terminals. Moderate to high confidence in VFR and diurnal winds prevailing through the TAF period. If a ceiling were to develop, it will likely be on the cusp of IFR/LIFR and take place in the 12Z-16Z time range. Fog is less likely, but some of the most pessimistic guidance has it.
(tonight through next Sunday) Issued at 421 PM PDT Tue May 19 2026
The northern outer waters will continue to see fresh northerly breezes with hazardous conditions through Thursday morning. The northerly breezes will also combine with an increasing northwest swell through Thursday morning with seas up to 12ft.
Ca, None. PZ, Small Craft Advisory until 3 PM PDT Thursday for Pt Arena to Pt Reyes 10-60 NM.
