, Issued at 1152 AM PDT Tue Mar 31 2026 (This afternoon through Thursday morning)
It only took 29 days, but it's finally raining. A stationary front is offering an area of convergence for its tropical moisture tap. Rain shower activity will continue to drift south through the day as surface high pressure tries to nose in from the Eastern Pacific Ocean. A gale force low in the Gulf of Alaska will put a stop to that as it heads to the Washington/Canada border. The attendant cold front will bring us a winter-like feel with below normal temperatures, gusty conditions, and rain. Southwesterly winds will increase ahead of the cold front with northwesterly winds developing in the post-frontal environment. Widespread gusts of 20-30 mph can be expected with gusts up to 40 mph in the highest terrain. Rainfall totals are expected to be in the 0.10"-0.25" range with locally higher totals in the higher terrain of the North Bay and locally lower totals in the Interior Central Coast. Slick roadways can be expected due to the dry spell that has allowed oil to accumulate.
..issued at 1152 AM PDT Tue Mar 31 2026 (Thursday night through next Monday)
The pattern will quickly change Thursday afternoon as upper-level shortwave ridging noses in from the Eastern Pacific Ocean. The short wavelength of the aforementioned trough and ridge will tighten the pressure gradient. Strong northerly winds will result, primarily affecting exposed areas like the higher terrain and marine environment. The SFO-WMC pressure gradient is expected to become negative Thursday night as the wavelength moves inland, resulting in offshore flow. At 5 AM Friday, the ECMWF Ensemble mean is forecasting the gradient to be -9.81 mb while the GEFS mean is forecasting the gradient to be -7.76 mb. The 2 mb discrepancy is due to the ECMWF Ensemble showing a stronger high and stronger low closer together than weaker features farther apart in the GEFS. This uncertainty is propagated through Friday and Saturday with the ECMWF Ensemble bottoming out at -10.96 mb at 5 AM Saturday while the GEFS is well on its relaxing trend at -5.24 mb. Nonetheless, a moderate offshore flow event can be expected Thursday night through the weekend with a 35 knot 925 millibar jet streak across the North Bay. This will translate to gusts of 40 to 50 mph in the higher terrain, namely the North Bay Interior Mountains, East Bay Hills, and Eastern Santa Clara Hills. The ridge will also send temperatures soaring back to well above normal.
(00z TAFS) Issued at 409 PM PDT Tue Mar 31 2026
Expect a mix of VFR/MVFR cigs through tonight and much of Wednesday morning. The bulk of rainfall tonight will wind down after sunset with some scattered light rain persisting over the Bay Area until midnight. Cigs will mostly remain between MFVR/VFR through the overnight hours. The North Bay terminals, especially KSTS is expected to drop to IFR cigs as rain moves through early Wednesday morning.
Vicinity of SFO, Expect VFR to prevail through much of the overnight, then dropping to MVFR around sunrise Wednesday amid the next round of scattered light rain across the Bay Area. Expect light southerly winds through most of Wednesday morning then becoming breezy out of the southwest Wednesday afternoon and eventually northwest behind the front Wednesday night.
SFO Bridge Approach, Similar as SFO.
Monterey Bay Terminals, VFR the remainder of this evening with MVFR cigs expected to develop late tonight through much of Wednesday morning with some scattered light rain activity possible overnight. Light southerly winds Wednesday morning become breezy out of the southwest behind a cold front Wednesday afternoon with VFR cigs persisting through the remainder of the forecast period.
(tonight through next Sunday) Issued at 409 PM PDT Tue Mar 31 2026
Rain showers will continue today around a surface low just beginning to enter our waters and along the associated stationary front. Gentle southwesterly breezes today will increase to become moderate to fresh tomorrow ahead of a cold front. Fresh to strong northwesterly breezes will develop in the post-frontal environment Wednesday night into Thursday morning. Strong northerly breezes will develop Thursday afternoon and persist into Friday. Moderate seas will build to become rough Thursday into Friday. Widespread hazardous conditions are expected Thursday and Friday. Conditions improve by the weekend.
Ca, None. PZ, Small Craft Advisory from 3 PM Wednesday to 3 AM PDT Thursday for Pt Arena to Pt Reyes 0-10 nm-Pt Arena to Pt Reyes 10-60 NM-Pt Reyes to Pigeon Pt 0-10 nm-SF Bay N of Bay Bridge.
