Marine Weather and Tide Forecast for San Mateo, CA

SHORT TERM
Issued at 1228 PM PDT Fri Oct 16 2026 (This evening through Saturday night)

The Red Flag Warning for the North Bay Interior Mountains was allowed to expire at 11 AM this morning as winds speeds continue to diminish. However, critical to near critical fire weather conditions prevail across the higher elevations of the Bay Area and north Central Coast through Saturday due to low relative humidity values.

Today remains on track to be the warmest day of the week as high pressure dominates the weather pattern aloft with areas of Moderate HeatRisk, especially near the coast. Interior areas will peak in the upper 80s to lower 90s. Coastal areas will remain mild to very warm in the 70s to mid 80s as weak onshore winds are forecast by early afternoon.

Tonight, lower elevations are forecast to cool into the 50s to lower 60s under mostly clear skies. The higher elevations are once again forecast to be warm and only cool into the 70s to lower 80s (attributing to the low relative humidities).

For Saturday, an increase in onshore winds and lack of offshore flow will result in a slight cooling trend in most areas. However, areas of Moderate HeatRisk are forecast to continue with temperatures forecast to be some 10-20 degrees F above seasonal averages.

LONG TERM
Issued at 1228 PM PDT Fri Oct 16 2026 (Sunday through next Thursday)

More of a zonal flow returns to the region on Sunday. This will result in temperatures cooling to near seasonal norms with the return of a marine layer and increased onshore winds. Upper level troughing deepens off of the West Coast through early next week, resulting in below average temperatures returning to the region. A cut-off low is forecast to develop off of the Bay Area and north Central Coast by Tuesday and is currently projected to push inland across southern California by Wednesday afternoon/evening. This will bring a slight chance to chance of rainfall to the region Tuesday through early Thursday morning. There is also generally a less than 15% chance of thunderstorm on Tuesday when the core of the cut-off low remains just off of the Central Coast. However, the trajectory of the cut-off low will largely impact which areas receive the most rainfall and/or any thunderstorm development. Thus, uncertainty remains relatively high. So be sure to check back on the forecast as we will likely gain more clarity in the forecast over the coming days.

What is most clear, the cool down! As the 500 mb clusters generally agree on the troughing off of the West Coast through much of next week. As best said by my colleague, "Bottom line: expect a pattern change to occur next week with below normal temperatures, potential for light rain, breezy to gusty onshore winds, and a low potential for thunderstorms."

AVIATION
(00Z TAFS)
Issued at 418 PM PDT Fri Oct 16 2026

High conf for VFR through the period with lingering offshore flow and dry air in the lower levels. Onshore returns tomorrow afternoon.

Vicinity of SFO...Onshore this evening then shifting NE overnight.
Onshore returns tomorrow afternoon.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Diurnal wind patterns with VFR conditions.

MARINE
(Tonight through next Wednesday)
Issued at 418 PM PDT Fri Oct 16 2026

High pressure over Eastern Pacific and a trough of low pressure along the California Coast will maintain gentle to moderate northerly breezes through Friday night. A cold front will sweep through increasing winds to become strong across the northern outer waters Saturday and Sunday. Moderate to fresh northwesterly breezes Monday will diminish and back to become westerly Tuesday.
Moderate seas will prevail through Saturday, building to become rough across the outer waters Saturday through Tuesday. Light rain is expected Monday into Tuesday.

FIRE WEATHER
Issued at 1228 PM PDT Fri Oct 16 2026

Conditions will remain very dry, with RH values around 10-20% forecast for the rest of the day and poor overnight recoveries tonight into Saturday. These conditions, combined with warmer weather, will lead to near critical weather conditions for the higher elevations of the Bay Area and Central Coast through Saturday. We will begin to see a reprieve in conditions Saturday into Sunday, as the upper level pattern shifts to broad troughing.
Temperatures become more seasonal and we should start to winds become onshore, improving RH conditions as well.

KR

BEACHES
Issued at 1021 AM PDT Fri Oct 16 2026

Hazardous beach conditions will be present at Pacific Coast beaches this weekend and likely into next week. Long period (17 seconds)
southerly/southwesterly swell will bring an increased risk for sneaker waves and strong rip currents with breaking waves of 7 to 12 feet. Remain off of jetties, piers, rocks, and other waterside infrastructure as waves can sweep across the shoreline without warning, pulling people into the sea. Remain out of the water to avoid hazardous surf with strong rip currents and never turn your back on the ocean!

Sarment

MTR WATCHES/WARNINGS/ADVISORIES
CA...Beach Hazards Statement from 3 AM PDT Saturday through Sunday evening for CAZ006-505-509-529-530.

PZ...Small Craft Advisory from 3 PM to 9 PM PDT Saturday for Pt Arena to Pt Reyes 0-10 nm.

Small Craft Advisory from 3 AM to 9 PM PDT Saturday for Pt Arena to Pt Reyes 10-60 NM.