Marine Weather and Tide Forecast for Sunnyvale, CA

SHORT TERM
Issued at 1208 AM PDT Tue Jun 9 2026 (Today and tonight)

Light showers are moving through the Bay Area as an incoming cold front drags some moisture through the region. These showers have overperformed a little, and we've gotten reports of a few hundredths of an inch of rain as far south as the Santa Cruz Mountains. With continuing bands of precipitation moving through, have added a chance for coastal and foothill drizzle across the Bay Area and Santa Cruz County through the night, but accumulations are still light and won't top a tenth of an inch across most of the Bay Area.

Today will mark the beginnings of a pattern change as an upper level trough over the Pacific Northwest starts to shift eastwards and allow a building ridge to come in from the Pacific. Today's highs will be seasonable to cool, but they will be slightly warmer than yesterday's with highs in the middle 70s to middle 80s throughout the inland valleys, up to the upper 80s and near 90 in the warmest spots of southern Monterey County, the upper 60s to middle 70s near the bays, and the upper 50s to middle 60s along the Pacific coast.

LONG TERM
Issued at 1208 AM PDT Tue Jun 9 2026 (Wednesday through Monday)

The pattern change will continue through Wednesday and Thursday as the ridge extends into the West Coast while the trough dips a little south of due east to create an inside slider-like setup, allowing for a dramatic warming of temperatures for the middle and latter parts of the week. In addition, strong northerly gusts and low humidities late on Wednesday into Thursday could result in elevated to near-critical fire weather conditions across the North Bay interior mountains, the Diablo range across the interior East Bay, and the eastern Santa Clara County mountains. For more information on the expected conditions, see the FIRE WEATHER section.

Hot temperatures on Wednesday and Thursday will contribute to Moderate HeatRisk across the inland regions, as high temperatures reach the 90s into the triple digits across the inland valleys, while temperatures reach the 80s to lower 90s close to the bays and the 60s to the middle 70s at the Pacific Coast. This corresponds to a moderate risk of heat-related illnesses, especially for people sensitive to heat including children, the elderly, pregnant women, people with chronic health conditions, and people who work or live outside without adequate cooling or shelter. People spending time outdoors should take frequent breaks in the shade and drink plenty of water.

The ridging pattern will persist Friday into the upcoming weekend with the ridge axis further developing into the northeast Pacific off British Columbia and the Alaskan panhandle, and the current forecast depicts a gradual cooling trend during that time persisting into the early part of next week. Confidence remains low regarding the time that a marine layer redevelops, but model output hints that the marine layer stratus could return as soon as Saturday or Sunday.
Conversely, without any major large-scale forcing to move the general ridging pattern away, temperatures could continue to trend warmer for Friday and the following weekend. The extended range outlook has around a 50-50 chance that temperatures remain above the seasonal average heading into the third week of June.

AVIATION
(18Z TAFS)
Issued at 1155 AM PDT Mon Jun 8 2026

VFR through the afternoon as high level clouds begin to move across the region as the low pressure system to our northwest moves onshore. MVFR ceilings begin to fill in at terminals beginning as early as 5pm PDT today and will be widespread by sunset. Moderate westerly winds (10+ kts) prevail through the afternoon and early evening with embedded gusts in excess of 20kts. Medium to high confidence that most terminals will develop IFR ceilings overnight, except for LVK and SJC where it will remain MVFR through Tuesday morning. Winds ease overnight and may become variable at times at some sites, but will predominantly come from the west unless otherwise stated in TAF. North Bay and coastal terminals have a 20- 30% chance of experiencing some drizzle (up to 0.01 inches) this evening through the overnight hours from the approaching upper-level trough, though confidence is currently too low to include in the TAF.

Vicinity of SFO...VFR and strong gusts prevail through the day into the evening. MVFR ceilings will settle over the Bay around 5pm as westerly winds begin to ease. Ceilings will become borderline IFR- MVFR around sunset time and eventually get pushed to IFR through the overnight hours. Conditions improve back to VFR by late Tuesday morning due to mixing. High confidence in forecast.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR through the afternoon as westerly winds increase to moderate breezes (10-15kts). Winds diminish slightly early evening (~5pm PDT) with developing MVFR ceilings that eventually become IFR through the overnight hours. Expecting conditions to transition back to VFR by Tuesday morning.

MARINE
(Tonight through next Sunday)
Issued at 940 PM PDT Mon Jun 8 2026

Breezy conditions linger in the inner waters south of Point Sur.
Expect winds to ease across the waters overnight, but northwesterly winds and seas will begin to build again Tuesday morning. This will lead to hazardous conditions for small craft to develop across the waters. Gale force gusts are expected by Tuesday night over the northern outer waters. Winds and seas begin to ease again into Thursday, and stay light through the weekend.

FIRE WEATHER
Issued at 1208 AM PDT Tue Jun 9 2026

Hot temperatures, gusty north winds, and low humidities across the North Bay interior mountains into the Diablo Range will raise the fire weather threats late on Wednesday into Thursday, with a particular emphasis on the interior mountains of Napa County.
Although the strongest winds will remain within the Sacramento Valley, gusts of 25 to 35 mph are expected to spread into Napa County and the Diablo Range south through Santa Clara County, with stronger gusts of 40-50 mph possible along the Vaca Mountains along Napa County's eastern edge. Meanwhile, daytime humidity retention will be very poor with relative humidity values as low as 10-15%, while overnight recoveries are likewise poor as RH values top out at 20-30%. Thus, fuels are expected to dry rapidly, leading to the elevated fire weather concerns. Also important to note that even with the drizzle and light rain coming through the region, wetting rains (rain totals above 0.1") are not expected, limiting any relief that will be realized for the midweek period. Elsewhere across the district, conditions remain hot and dry, but we're not expecting winds to be as strong as they are across the interior North Bay.

We are continuing to monitor the potential for fire weather products to be issued for the interior mountains of the North, East, and South Bays for Wednesday and Thursday. At present, conditions are right on the edge of critical fire weather criteria, but the confidence isn't there at this point to pull the trigger on any warnings. The day shift will reevaluate the fire weather forecast for Wednesday and Thursday and in collaboration with neighboring offices, will be in a better position to determine the extent of necessary products. Regardless of whether any products are issued across the interior, elevated to near critical fire weather conditions are still forecast and care must be taken to avoid starting a fire that could spread rapidly. Remember, one less spark, one less wildfire.

DialH

MTR WATCHES/WARNINGS/ADVISORIES
CA...None.
PZ...Small Craft Advisory from 9 AM this morning to 9 PM PDT this evening for Mry Bay-Pt Arena to Pt Reyes 10-60 NM.

Small Craft Advisory from 9 AM to 9 PM PDT Wednesday for Mry Bay.

Small Craft Advisory from 9 AM this morning to 9 PM PDT Wednesday for Pigeon Pt to Pt Pinos 0-10 nm-Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 0-10 nm-Pt Pinos to Pt Piedras Blancas 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm.

Small Craft Advisory until 3 AM PDT early this morning for Pt Pinos to Pt Piedras Blancas 0-10 nm.

Gale Warning from 9 PM this evening to 9 PM PDT Wednesday for Pt Arena to Pt Reyes 10-60 NM.