Marine Weather and Tide Forecast for Mountain House, CA

SHORT TERM
Issued at 1147 PM PDT Sun May 17 2026 (Tonight through Monday)

An upper level low pressure system digs into the tri-state area of CO, UT, and WY by late Monday morning. We remain under the influence of the broader trough associated with it, leading to breezy offshore flow. North to northeast winds pick up tonight across the Santa Cruz Mountains, the interior North Bay Mountains, and the Eastern Santa Clara and East Bay Hills. Sustained wind speeds of 15 to 30 mph along with gusts up to 50 mph, though localized gusts up to 60 mph are expected for favored ridges, gaps, and passes. These winds will usher in drier air to the region as well, keeping the fire weather threat elevated for interior Bay Area and Central Coast locations.
In terms of more every day hazards from the winds, impacts include, but are not limited to difficult driving, especially for high profile vehicles, downed tree limbs, the potential for power outages, and the possibility of loose or unsecured items being blown around.

Winds begin to ease late Monday morning into the afternoon and will continue to decrease into the evening and overnight hours. Offshore winds should bring some warmer temperatures to the region, the 90s for the interior Bay Area valleys, the 60s to low 70s along the coast, and the mid 70s to low 80s for the Central Coast Valleys.

LONG TERM
Issued at 1147 PM PDT Sun May 17 2026 (Tuesday through next Sunday)

Upper level troughing looks to hold just west of the Desert Southwest and into southern CA Tuesday into Wednesday, leaving us with teetering between quasi-zonal and barely trough-y. Weak offshore lingers at least over the interior mountain ranges through Tuesday into Wednesday, with onshore flow trying to make a diurnally driven push each afternoon/evening. During this time high pressure just to the west of us (over the eastern Pacific) builds, pushing towards the coast mid week. The upper level trough begins to meander south to southwest of southern California late week. This should bring a return of onshore flow to the region and perhaps the marine layer. Current guidance suggests we could see a 500ft marine layer return by Wednesday, with a 1000-1200ft marine layer by Thursday and Friday. Will need to keep an eye on this as it will affect how temperatures pan out.

AVIATION
(12Z TAFS)
Issued at 449 AM PDT Mon May 18 2026

Strong winds aloft continue to move through the region causing widespread LLWS (both in speed and directions)into the mid to late morning. Gusty winds will be possible across most sites north of the Monterey Bay through the morning. Winds aloft decrease into the mid to late morning and begin to match up with moderate to breezy surface winds. The general wind pattern switches from northerly to westerly into the night, with winds becoming light into the late night. Haze from sea spray will continue to affect the coast.

Vicinity of SFO...VFR through the TAF period. Gusty northerly winds continue to affect the terminal with even stronger winds aloft, leading to LLWS. Winds aloft reduce slightly and align better with gusty surface winds in the mid morning. Gusts reduce into the mid afternoon and winds turn more northwest before winds turn light into the night.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR through the TAF period. Surfaces wind stay light through the morning with stronger winds aloft continuing to offer LLWS. Expect surface winds to increase and turn northwest into the late morning, while winds aloft reduce. Moderate northwest winds will ease and become light into the night, with MRY going southerly.

MARINE
(Today through Saturday)
Issued at 449 AM PDT Mon May 18 2026

Winds are reducing across the marine environment, but widespread gale- force gusts are no longer expected. Seas and winds will still offer hazardous conditions for small craft into the mid weak before easing for most zones. Winds will remain hazardous for small craft into the late week for the northern outer zone.

FIRE WEATHER
Issued at 449 AM PDT Mon May 18 2026

Strong and gusty north to northeast winds continue to affect the region. Expect peak gusts greater than 30 mph for most areas, with around 45 to 55 mph along through gaps and passes, and across higher terrain. These winds will begin to reduce in the late morning but remain breezy until the late night. Daytime humidity retentions loos to stay around 10- 25% across the interior regions and higher peaks, with limited overnight humidity recoveries.
Humidities will be slow to recover into the work week as a light offshore flow will continue to affect the district.

BEACHES
Issued at 449 AM PDT Mon May 18 2026

A Beach Hazards Statement remains in effect for west facing beaches along the Pacific Coast through 9 AM due to strong winds over the marine environment leading to hazardously strong wind waves and overall rough seas. Dangerous swimming, boating, and surfing conditions can be expected. Large breaking waves can overpower swimmers resulting in significant physical injury and increase the risk of drowning. Gusts will stay strong along the immediate coast, causing blowing and drifting sand and increased sea spray. Water rescue attempts may be hampered by reduced visibilities from the sea spray. Remember, NEVER turn your back on the ocean.

MTR WATCHES/WARNINGS/ADVISORIES
CA...Beach Hazards Statement until 9 AM PDT this morning for CAZ006- 505-509-530.

Wind Advisory until 11 AM PDT this morning for CAZ504-512-514- 515.

Coastal Flood Advisory until 3 AM PDT Tuesday for CAZ506.

PZ...Gale Warning until 9 AM PDT this morning for SF Bay N of Bay Bridge.

Small Craft Advisory until 9 PM PDT this evening for Mry Bay- Pigeon Pt to Pt Pinos 0-10 nm.

Small Craft Advisory until 3 AM PDT Tuesday for Pt Arena to Pt Reyes 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm.

Small Craft Advisory until 9 AM PDT this morning for Pt Pinos to Pt Piedras Blancas 0-10 nm.

Small Craft Advisory until 3 AM PDT Wednesday for Pt Arena to Pt Reyes 10-60 NM.

Small Craft Advisory until 9 AM PDT Tuesday for Pigeon Pt to Pt Pinos 10-60 NM.