Swell Matrix

Area Forecast Discussion

National Weather Service San Francisco CA

1058 am PDT Sun may 3 2026

Short Term

, Issued at 1004 AM PDT Sun May 3 2026 (This afternoon through Monday)

It's a cloudy morning across the Bay Area and Central Coast with the stratus deck extending far inland, with a strong upper level low moving over the region allowing for remarkable expansion of the marine layer, to the point where it no longer makes sense to talk about a marine layer depth. KMUX radar returns are also showing light rain showers and drizzle across the San Mateo Peninsula, parts of Santa Clara County, and the Monterey Bay region, with the potential for additional drizzle where the radar beam is overshooting the low level processes, such as the North Bay and southern Monterey County. Drizzle chances diminish after around 1 PM, and some breaks in the clouds may develop across the inland regions this afternoon, but this is a lower confidence forecast. Have decreased the high temperature forecast across the region in light of the potential for continued cloudiness through the day. Highs in the lower to middle 60s are expected in the Bay Area interior valleys, the lower to middle 70s in the southern Salinas Valley, and the middle 50s to lower 60s along the coast and Bays. Conditions are broadly similar on Monday as the upper level low moves over the state, with additional cooling expected in the southern parts of Monterey County as highs reach the middle to upper 60s.

A Beach Hazards Statement remains in effect through 11 PM this evening due to long period northwesterly swell, an increasing risk of sneaker waves and strong rip currents. See the BEACHES section for more information.

Long Term

..issued at 1004 AM PDT Sun May 3 2026 (Monday night through next Saturday)

The upper level low continues to move across California through Tuesday, resulting in a continuation of the cool temperatures, extensive stratus decks, and a slight chance for light rain and drizzle across the region, but mainly at the coast and within topographically favored locations. The latest model output shows the low descending into southern California, allowing for a band of moisture to wrap around the low and bring some wetting rains to the North Bay Monday night into Tuesday morning. The current forecast shows rain totals of up to a quarter of an inch in the interior regions of the North Bay with totals a few hundredths of an inch closer to the coast and extending into the Bay Area. Of note, high resolution model output continues to show the possibility of higher rain totals, up to around half an inch in the North Bay, which might be possible if there are some particularly strong showers across the rain band. Flooding concerns remain minimal and focused on areas of exceptionally poor drainage or where drainage pipes are blocked or clogged.

By Wednesday, the upper level low moves into the Great Basin and southern Rockies with ridging building back behind it, leading to a warming and drying trend in the region with highs rising to the 70s and 80s inland. The CPC extended outlook shows that temperatures above the seasonal averages are likely to persist through the middle of May, while precipitation totals lean below the seasonal average. For context, the seasonal average high in downtown San Francisco is around 64 degrees, while the seasonal average precipitation total for the May 10 to 16 period, as covered in the CPC 8-14 day outlook, falls a shade under two tenths of an inch for the same station.

Aviation

(18z TAFS) Issued at 1059 AM PDT Sun May 3 2026

Upper low west of SFO will keep cloud bases high today, generally above 3000 feet but with only partial clearing this afternoon before widespread cloud cover refills overnight. Some isolated showers and drizzle remain possible as well, especially for coastal areas from Half Moon Bay to Salinas/Monterey late night and morning hours.

Vicinity of SFO, Expecting persistent cigs from 3000-3500 feet through Monday with best chance of periods of Scattered clouds during the afternoon hours but not expected to last long given the synoptic pattern.

SFO Bridge Approach, Similar to SFO under this pattern as the marine layer has been lifted into a higher based cloud deck.

Monterey Bay Terminals, Persistent cloud heights around 3000 feet this afternoon through Monday with only occasional breaks in the clouds afternoon hours. Periods of drizzle possible Monday morning 13-17z.

Marine

(today through Friday) Issued at 438 AM PDT Sun May 3 2026

An upper level low over the region will keep pressure gradients light near the surface allowing for continued light winds across the coastal waters today into early next week. A long period swell is passing through the waters with generally light seas. NW wind and seas will begin to build later in the week and into next weekend.

Beaches

Issued at 1004 AM PDT Sun May 3 2026

Long period northwest swell, with periods of 15 seconds or above, is now being reported on the offshore buoys and has either made it to the coast, or will arrive imminently. These long period swells increase the risk of sneaker waves and rip currents, particularly as the period between swell impulses results in lulls of around 20 to 30 minutes before larger sets of waves arrive. Due to the dangers, a Beach Hazards Statement for all Pacific coast beaches remains in effect until 11 PM Sunday night. Never turn your back to the ocean! Don't be fooled by calmer seas; observe the waves for at least 20 minutes before approaching the coast.

Watches, Warnings, Advisories

Ca, Beach Hazards Statement through this evening for CAZ006-505-509- 529-530.

PZ, None.

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