San Francisco woke up today under a stubborn blanket of marine layer, with mid 50s temperatures and low clouds hugging the waterfront. It was about 54°F at SFO at daybreak, with a slight chance of light drizzle before the sky starts to brighten. Memorial Day itself looks cool and partly sunny, with highs near 62°F. By afternoon, west-southwest breezes will crank up, with gusts into the 20s possible at exposed shoreline spots. The real punch arrives Tuesday, when stronger northerly winds are expected to rough up the bay and trigger advisories for some offshore waters.
Morning Drizzle, Cool Highs
The marine layer is about 2,500 feet deep and should peel back by late morning, though coastal hills and the immediate shoreline could remain gray a bit longer. Between about 8 a.m. and 11 a.m., a few hundredths of an inch of drizzle are possible. Afternoon highs should top out around 62°F, then slide toward 60°F as the onshore flow strengthens.
Stronger North Winds Tuesday
An upper-level trough is expected to swing through tomorrow, turning winds north to northwest and cranking them up along the outer coast, ridgelines and through gaps. Gusts could reach 30 to 40 mph in those exposed spots. Offshore waters are forecast to see winds of 20 to 30 knots with seas building to 8 to 14 feet in places. Small Craft Advisories are in effect for several marine zones tomorrow. Details are posted by the National Weather Service.
What This Means For Plans
For shoreline plans, think layers, including something windproof for the afternoon. Boaters should consider staying in port or shifting to more sheltered harbors on Tuesday, and ferry riders can expect choppy crossings and possible delays. Anyone hosting outdoor Memorial Day gatherings should secure tents, canopies and decorations, and keep an eye on the latest marine forecast before heading out on the water.
The trough should begin to relax by midweek, allowing temperatures to bump up into the upper 60s by Wednesday. Updates will follow if any watches or warnings expand, and it is worth checking official forecasts before committing to time on the water.
