Issued at 752 AM PDT Wed Jul 15 2026
Coastal stratus is hugging the Golden Gate, indicating signs of a returning marine layer! Thus, temperatures are cooler than 24 hours ago by a few degrees near the coast and into the coastal adjacent valleys. However, this afternoon will be equally as warm as yesterday across the interior with temperatures reaching into the 90s to around 103 deg F. Hot, dry, and breezy onshore winds will result in elevated fire weather conditions through Thursday, especially away from the coastal influences.
Remember: - Stay hydrated and drink plenty of fluids. - Wear lightweight, light-colored clothing. - Reduce time spent outdoors or stay in the shade. - Never leave people or pets unattended in vehicles. - Use sunscreen if going to the coast or the pool.
RGass
, Issued at 1139 PM PDT Tue Jul 14 2026 (Tonight through Thursday)
It was hot Tuesday. San Francisco hit 76, Santa Rosa 97, Livermore 102, and San Jose 95. I made the mistake of baking bread in the afternoon and my house in Monterey got to 81 degrees. The highs were about 5 degrees warmer than forecast, driven by strong high pressure to the east and totally clear skies. The 03Z WPC Surface Analysis shows a mesoscale 1019 mb high over northern Nevada that was stronger than expected. The 6-member PGE WRF ensemble (POMMS EPS) predicted the SFO-WMC gradient would be between +3 and +4 mb at 04Z, and it was actually observed at -3.8 mb. In other words the weather models missed this mesoscale high pressure over Nevada. This helped keep the air dry today and discouraged the marine layer from reforming. Temperatures are going to remain relatively warm overnight, but not quite as warm as last night thanks to the clear skies and enhanced radiational cooling. Similar high temperatures are expected Wednesday afternoon with slightly stronger winds in the afternoon as a trough starts to approach the coast. The overnight temperatures will cool much more effectively Wednesday night.
With the hot temperatures, low humidity, and moderate onshore winds, fire weather conditions will be elevated Wednesday and Thursday. A few stations are currently reporting red flag conditions across the North and East Bay. This will continue over the next couple days. Wednesday is hot and dry with moderate winds. Thursday will be a little cooler, but the winds will be a bit stronger. The elevated fire weather will continue through the nights as well. The lack of marine layer and strong thermal belting will keep higher elevations warm with poor humidity recoveries.
..issued at 1139 PM PDT Tue Jul 14 2026 (Thursday night through next Tuesday)
A cooling trend starts Thursday as a low pressure trough approaches the coast. There has been a slight change from yesterday however. It now looks like the Rocky Mountain 500 mb high will remain strong enough to force the incoming low north into the Pacific Northwest. The associated trough will still bring us cooler temperatures, but maybe not as drastic or quick as we thought yesterday. Temperatures will be about 5 degrees above normal Thursday, near normal Friday, and 5 degrees cooler than normal over the weekend and into early next week. The marine layer will also start to reform during this cooling trend, with low clouds likely to return to the typical gloomy areas by Friday morning.
The large scale mid level flow will stay out of the SW between the fairly stationary Eastern Pacific trough and central US ridge. This keeps the conveyer belt open for surges of tropical moisture, particularly if a recurving tropical cyclone drags some of the deep tropical moisture into the subtropics. We now have a tropical cyclone in the NE Pacific near 15N, 110W named TROPICAL DEPRESSION FIVE-E. This system is expected to become a hurricane by Thursday and continue NW through the weekend. Depending on the track and the ultimate strength of this tropical cyclone, it has the potential to bring moisture far enough north to be sucked into the conveyer belt and delivered to the Bay Area. The uncertainty is pretty high with tropical cyclone tracks, but it looks likely that there will be some moisture arriving Sunday or Monday from this system. The amount of moisture is still up in the air. The ECMWF ensemble mean has dropped from 1.0" yesterday to 0.8" today (90th percentile to 75th percentile), but the spread between members remains quite large. Why do we care about this? Elevated moisture surges bring the potential for high based thunderstorms and dry lightning that can spark wildfires.
(18z TAFS) Issued at 1042 AM PDT Wed Jul 15 2026
VFR conditions prevail across all terminals. High confidence in VFR through the afternoon with low to moderate confidence on IFR ceilings returning to the coastal terminals of HAF, MRY, and SNS tonight. Diurnal winds will prevail.
Vicinity of SFO, Currently VFR with westerly flow. High confidence in VFR and diurnal winds prevailing through the TAF period. Wind gusts are anticipated to reach 30 knots with occasional gust to 35 knots possible between 23Z and 03Z this afternoon.
SFO Bridge Approach, Low probability (20-30% chance) of low clouds below FL045 developing across the San Mateo Bridge Approach tonight.
Monterey Bay Terminals, VFR conditions prevail with light winds over MRY and northwesterly winds over SNS. Moderate confidence on IFR ceilings returning to the terminals tonight.
(today through Monday) Issued at 424 AM PDT Wed Jul 15 2026
Widespread hazardous conditions for small craft are expected into Friday across the inner and outer waters due to fresh to strong northwesterly breezes. Gale force gusts are expected along the coastal jet regions of Point Reyes and Point Sur. The afternoon sea breeze will create hazardous conditions for small craft within the bays. Moderate seas will prevail with intermittent rough seas in the outer waters through Friday.
Ca, Coastal Flood Advisory until 4 AM PDT Thursday for CAZ006-506- 508.
Heat Advisory until 10 PM PDT this evening for CAZ516-517.
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 from 9 AM to 3 PM PDT Thursday for Mry Bay.
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.
Small Craft Advisory until 9 AM PDT Thursday for Pt Pinos to Pt Piedras Blancas 0-10 nm.
Gale Warning from 9 AM to 3 PM PDT Thursday for Pt Pinos to Pt Piedras Blancas 0-10 nm.
