Issued at 1000 AM PDT Tue Aug 4 2026
Two updates to the forecast this morning:
1)Solid marine layer push this morning with ample coverage along the coast. Despite the coverage it's still rather compressed. Compressed nature and topographic enhanced has yielded drizzle here at the office in Monterey. The chance of drizzle will decrease through 11 am as the marine layer clears back to the coast.
2)Expanded today's heat advisory to now include the Santa Clara Valley and Santa Clara Eastern Hills. Upon further analysis and fine tuning of temperatures HeatRisk coverage of Moderate to near Major for Heat Advisory expansion. Keep in mind heat impacts can be cumulative and today some of these locations have been over 90 degrees since Saturday.
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, Issued at 148 AM PDT Tue Aug 4 2026 (Today and tonight)
The southerly surge of stratus that arrived earlier on Monday, has allowed for stratus to become more widespread this morning. Nearly all of our coastline has low clouds along it, with the stratus penetrating inland. The Monterey Bay along with the majority of the Salinas Valley has filled in, is slowly creeping into Bay Area. Expect the marine layer to about 800-1000ft, which should keep high temperatures for coastal communities and areas in or under the marine layer reasonable. Clouds will begin retreating to the coast by mid to late morning, leaving mainly clear skies across the region. In terms of the upper level pattern, high pressure will slowly take hold of the forecast. 850mb temperatures today, look to to be between 24-29C, warmest across the interior. Expect temperatures to a bit cooler than yesterday for areas influenced by the marine layer, while other locations remain hot. Patchy Moderate HeatRisk exists interior North Bay and interior Monterey, with areas to widespread Moderate HeatRisk for interior East and South Bays. Opted to hold off an issuing a Heat Advisory for these locations tonight until we get a better visual on the marine layer expansion since that could put interior temperatures at risk.
..issued at 148 AM PDT Tue Aug 4 2026 (Wednesday through Monday)
No major changes to the forecast as high pressure will continue to build into the region and then hold through at least Saturday. Temperatures will may decrease a more degrees on Wednesday, but it will be dependent on the marine layer. Interior locations will still be warm, but likely have temperatures in the 90s, perhaps cracking 100 in a few spots. Warmer and dryer weather starts to return on Thursday as the ridge strengthens. Looking at models, 850mb temps don't really deviate too much. We're still looking at that airmass being warm, around 27-30C, depending on the model. Overnight lows would be mild, especially in the thermal belts/mountains. And day time highs would climb back into the 90s and low 100s. The HeatRisk projection looks to have widespread Moderate HeatRisk for interior slots, with pockets of Major HeatRisk. Heat Advisories may be needed.
(18z TAFS) Issued at 1036 AM PDT Tue Aug 4 2026
MVFR-IFR stratus continues to clear out of the SF Bay and Monterey Bay regions, and is expected to linger at the immediate coastal regions. Gentle to moderate onshore winds are expected to develop in the afternoon and evening with speeds of around 10 to 15 kt. Stratus will return to the valleys tonight, with some more inland expansion expected. Moderate confidence in stratus impacts at SJC overnight into Wednesday morning. Smoke transport from fires across the Pacific Northwest may result in impacts to slant visibility due to hazy conditions.
Vicinity of SFO, Stratus has cleared out somewhat early as light southerly flow impacted the terminal, with the winds turning to the northwest this afternoon and evening, as speeds reach 10 to 15 kt. MVFR-IFR stratus will return to the terminal region tonight, and persist into Wednesday morning. Winds will turn more to the west and the southwest at around 10 kt for Wednesday afternoon.
SFO Bridge Approach, Similar to SFO.
Monterey Bay Terminals, SNS has scattered out to VFR, with VFR conditions continuing through the afternoon. At MRY, IFR-MVFR stratus continues through the morning with moderate to high confidence that a brief period of VFR skies develops in the afternoon and early evening hours. Moderate northwest winds will develop in the afternoon and evening hours, becoming light overnight as LIFR-IFR stratus returns to the region. Clearing of the stratus is not expected until after the end of the TAF period.
(today through Sunday) Issued at 1000 AM PDT Tue Aug 4 2026
Light to gentle breezes will persist across the majority of the coastal waters through late week. A localized gentle to moderate breeze continues across the inner waters. Seas continue to abate with wave heights between 4-8 feet expected through the later part of the week. The Pacific High strengthens and shifts eastward late this week into the weekend, resulting in strengthening winds and building seas with a return of hazardous conditions for small craft.
Ca, Heat Advisory until 10 PM PDT this evening for CAZ510-513>515.
PZ, None.
