Weather
San Francisco, CA Weather: Rain Chances Rise to 50% Wednesday, Oct. 21
San Francisco, CA – A noticeable cooldown arrives across the San Francisco Bay Area and Central Coast Sunday, Oct. 18, with rain chances expected to increase significantly by Tuesday and Wednesday. So
By Miles Carter · 2026-10-18T08:48:59.771Z
San Francisco, CA – A noticeable cooldown arrives across the San Francisco Bay Area and Central Coast Sunday, Oct. 18, with rain chances expected to increase significantly by Tuesday and Wednesday. Some coastal communities could see precipitation probabilities climb as high as 70% by midweek.
According to the National Weather Service San Francisco Bay Area/Monterey office, much cooler weather arrives Sunday, followed by rain likely in portions of the region during the middle of the week.
The latest precipitation forecast shows relatively dry conditions Sunday and much of Monday before rain chances begin increasing Tuesday, Oct. 20.
When will rain chances increase?
Rain probabilities begin climbing Tuesday across San Francisco, Oakland, San Jose, Monterey and surrounding communities.
By Wednesday, Oct. 21, the National Weather Service forecasts precipitation probabilities reaching approximately 50% around San Francisco and Oakland, with similar chances across several inland Bay Area communities.
Farther south, the potential is greater.
Big Sur could see rain probabilities reach 70%, while Monterey, Salinas and King City approach 65% during portions of Wednesday.
Santa Cruz, Hollister and several other Central Coast communities could experience precipitation chances around 55% to 60%.
Will the rain last all week?
The forecast suggests precipitation chances will begin decreasing Thursday, Oct. 22, with considerably lower probabilities expected Friday, Oct. 23.
For now, the most favorable window for widespread showers appears to be Tuesday night through Wednesday, although timing and coverage may change.
Residents should prepare for potentially wet roads during midweek commutes, especially where showers become more persistent.
Looking ahead: NOAA's Oct. 25 31 outlook favors cooler than normal temperatures and above normal precipitation across portions of California, suggesting unsettled weather could remain a concern heading toward Halloween.
However, that longer range outlook does not establish whether rain will fall on Halloween night.
For now, the immediate forecast highlights a Sunday cooldown followed by increasing rain chances Tuesday and Wednesday.