, Issued at 1201 AM PDT Thu Apr 23 2026 (Today and tonight)
KMUX has been allowed to transition back into clear air mode as shower activity has ended across the region. Relatively moist conditions and light winds overnight will lead to some potential for patchy fog to develop across the valleys. Latest HRRR guidance supports a slightly higher chance for patchy fog to develop within the Santa Clara Valley and potentially within North Bay Valleys. Fog development would be most likely in the early morning hours/right around sunrise. As this may run into the early morning commute, if you encounter fog remember to slow down and allow extra time to reach your destination.
Morning temperatures will be seasonable with lows generally in the 40s. Portions of the Eastern Santa Clara hills, the Gabilan Range, and the Santa Lucia Range will drop into the mid to upper 30s. High temperatures warm up well, however, as a weak, progressive ridge moves through southern and central California. High temperatures will be in the low to mid 70s across the interior and 50s to 60s along the coastline. Temperatures across the lower elevations will be seasonal to seasonally warm while temperatures across the higher terrain are below normal. No other concerns in the short term as dry weather prevails. Winds remain light and onshore today with diurnally breezy conditions expected across the valleys.
..issued at 1201 AM PDT Thu Apr 23 2026 (Friday through Wednesday)
By Friday, the upper level ridge will begin its eastward exit and weak upper level troughing will return over the Western US. This trough is associated with a deep upper level low that will remain situated over Montana/the Dakotas through the weekend before exiting the region early next week. As weak troughing returns, it will allow a much cooler airmass to filter in over the West Coast Saturday through early next week. Initial guidance shows 850 mb temperatures running between 2-4 degrees Celsius which is between the 10th to 25th percentiles for 850mb temperatures recorded by OAK. For comparison the daily mean 850 mb temperatures are closer to 7 to 8 degrees Celsius. What does that look like at the surface? High temperatures on Friday will be fairly seasonal in the upper 60s to low 70s across the interior and 50s to 60s along the coast. Saturday temperatures will cool by around 5 degrees across the interior where widespread 60s are expected (coastal temperatures remain in the 50s to 60s). We can expect similar temperatures on Sunday before a slight warming trend kicks off Monday as 850mb temperatures warm (becoming more seasonal). This warming trend will see temperatures returning to the low to mid 70s across the interior with temperatures warming by a few degrees each day through the remainder of the long term forecast. Overnight low temperatures remain seasonable through the extended forecast with slightly cooler temperatures expected across the higher elevations of the eastern Santa Clara Hills, the Gabilan Range, and the Santa Lucia Range.
Another factor to consider in planning your weekend is the possibility of rain. Currently, it is looking like we might get some light rain but it will not be as impressive as the system we just had. Ensemble guidance is alternating between drizzle to a few tenths of an inch (0.1-0.2") possible. The higher chances for light rain are across the Central Coast with more drizzly conditions likely across the Bay Area. Higher precipitation totals (compared to us) are more likely across Southern California where the main moisture plume is oriented against. Either way, it is likely to be a drizzly weekend but the incoming rain will be light and beneficial. Ensembles are hinting at additional light, beneficial rain being possible mid to late next week as the upper level pattern remains unsettled.
(18z TAFS) Issued at 1141 AM PDT Thu Apr 23 2026
Quiet weather with some fair weather cumulus clouds popping up over the region and high clouds passing overhead. VFR conditions will prevail through the evening and perhaps early overnight hours for most sites. Guidance suggests that a mix of stratus and fog will return at some point, but there are some caveats. High clouds could disrupt fog and stratus formation, in addition to winds. Trended towards KAPC and KSTS seeing another night of reduced ceilings and visibility, with KHAF likely joining them. The models are bit divided on the expanse of the stratus and fog, thus I opted to hint at lowering cigs for KSJC and KLVK. Medium to high confidence in the forecast.
Vicinity of SFO, Onshore flow is expected to return this afternoon, and increase to around 15kt around 0Z. This will last into the late evening hours with winds falling below 10kt near or after 7Z. Quite a few models indicate MVFR ceilings moving into the Bay, with much of the Bay seeing MVFR cigs increase between 11-14Z and continuing until at least 17-18Z. Opted to go with a slightly more optimistic forecast with cigs clearing between the 17-21Z. Medium confidence in the forecast.
SFO Bridge Approach, Similar to SFO.
Monterey Bay Terminals, VFR conditions prevail for the majority of the region for the afternoon with high clouds streaming overhead and cumulus popping up over the mountains. Much like the discussion above, stratus and any associated fog may be dependent on the high clouds and winds. Guidance shows Monterey Bay with ceilings around 035-050 for heights, though a few bring KMRY closer to MVFR status. Expect this to occur just before or around sunrise, before mixing out by mid to late morning.
(today through Tuesday) Issued at 924 AM PDT Thu Apr 23 2026
Moderate north breezes this morning will develop into a northwest breeze this afternoon. Choppy seas at times today will begin to subside Friday and continue into the weekend. Light rain and drizzle return to this weekend.
Ca, None. PZ, Small Craft Advisory from 3 PM this afternoon to 9 PM PDT this evening for Pigeon Pt to Pt Pinos 0-10 nm-Pt Arena to Pt Reyes 0-10 nm-Pt Pinos to Pt Piedras Blancas 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm.
Small Craft Advisory until 9 AM PDT Friday for Pt Arena to Pt Reyes 10-60 NM.
Small Craft Advisory from 3 PM this afternoon to 3 AM PDT Friday for Pigeon Pt to Pt Pinos 10-60 NM.
