Issued at 914 PM PDT Mon Aug 17 2026
Stratus has begun to push inland with less coverage expected than last couple nights as the marine layer depth begins to gradually decrease with increasing influence of the upper level ridging to our east the next couple of days. Overnight lows will once again be mild with mid/upper level cloud cover continuing to stream across our area from southwest to northeast. Temperatures Tuesday will be slightly above normal, the subtle warmup will continue Wednesday before moderating back closer to or slightly below normal by Thursday.
, Issued at 200 PM PDT Mon Aug 17 2026 (This evening through Tuesday night)
Water vapor imagery continues to show an elongated upper level trough off the West Coast this afternoon, with the parent low centered near 32.5 North and 137.5 West. There are several disturbances moving around this trough, including the one lifting across southwest Oregon that brought all of the high cloud cover to Central and Northern California today. Water vapor imagery also shows high pressure over the Desert Southwest, with California remaining between the two large scale features, with relatively moist southwesterly flow aloft over us. Unfortunately, all of moisture is in the upper atmosphere in the form of high clouds. There has been enough breaks in these clouds though that our daytime temperatures today are warming more than I initially gave them credit for. In fact, most locations are running 3 to 6 degrees warmer today over yesterday. That is in part to the warmer start to the day, but also the combination of increasing 850 mb temperatures, a compressing marine layer, and then sunshine. The question now is whether or not there will be enough clouds to be another insulating blanket tonight? Looking at the IR imagery, think this is a plausible solution, and expect mild conditions once again tonight. The marine layer will return again tonight, but should be shallower (around 1500 feet), and not be quite as widespread as this morning.
The upper level ridge, despite being dirty, will be the dominate weather feature for Tuesday and Tuesday night, helping to continue to minor warming trend, especially across the inland areas. Despite the minor warming trend, daytime temperatures will remain near to below normal through for most areas, with just the far inland areas being above normal. The marine layer will also start to compress, with more patchy fog possible during the late night and early morning hours. Palmer
..issued at 200 PM PDT Mon Aug 17 2026 (Wednesday through next Sunday)
This upper level ridge will remain our more dominate weather feature at least Wednesday and potentially now into Thursday. Therefore, expect inland areas to potentially see another degree or two of warming on Wednesday, with little change for Thursday, while coastal areas only see minor fluctuations, as a shallow marine layer lingers along the coast.
The upper level low currently near 32.5 North and 137.5 West will finally lift for Friday before moving into the Pacific Northwest for the weekend. This will once again bring a deeper marine layer, stronger onshore winds, and cooler conditions to the Bay Area and Central Coast once again. That being said, the parent trough will remain off the California Coast as another upper level low replaces this first one. While the details are still not entire clear on where this secondary parent low will set up, it will keep California with south or southwesterly flow aloft through the first part of next week. The East Pacific also looks to get active with a series of easterly waves during this time. This could make things a little more interesting around here, should something try to form and slip north around the edge of the ridge. At this point in time, that does not look likely, but can't fully rule it out either. Needless to say, this is something that will bears watching. For now though, expect continued dry through the period. Palmer
(06z TAFS) Issued at 959 PM PDT Mon Aug 17 2026
IFR-LIFR stratus is expanding inland with high clouds making it difficult to gauge the extent of the stratus deck in several areas across the North Bay and SF Bay regions, while a moderate northwest breeze persists for a couple more hours. Stratus will generally impact most of the terminals through the overnight period with low confidence of impacts at LVK. May need to monitor observations to see if the high clouds result in impaired stratus development at STS. Stratus will mix out back to the coastal regions on Tuesday morning, with gentle to moderate onshore breezes developing in the afternoon and evening. Tuesday night, expect lower ceilings and less inland stratus development near and beyond the end of the TAF period as the marine layer continues to compress.
Vicinity of SFO, IFR stratus continues through the night with lingering moderate winds diminishing in the next couple of hours. The stratus deck will mix out on Tuesday morning with breezy northwest winds resuming in the afternoon. Tuesday night, the terminal area sits at the edge of where high resolution model output paints the stratus deck, making the forecast for stratus impacts and development time low to moderate confidence.
SFO Bridge Approach, Lower confidence for stratus impacts on Tuesday night compared to the terminal area. Otherwise similar to SFO.
Monterey Bay Terminals, IFR stratus has developed across the region with a decrease to LIFR ceilings expected through the night. The stratus will mix out through Tuesday morning, with some uncertainty on clearing times. Moderate confidence that MRY will scatter out sometime Tuesday afternoon. Light winds will persist through Tuesday morning before gentle to moderate northwest winds resume in the afternoon and evening. Opted for a persistence forecast for IFR-LIFR stratus returning to the terminals early Tuesday evening.
(tonight through next Sunday) Issued at 914 PM PDT Mon Aug 17 2026
A fresh to strong northwest breeze will develop tonight and persist through the end of the forecast period. Locally stronger winds are possible in the coastal jet regions north of Point Reyes and along the Big Sur coast. Seas build to 7 to 9 feet by Tuesday and Wednesday before subsiding later in the week.
Ca, None. PZ, Small Craft Advisory from 3 AM Tuesday to 3 AM PDT Wednesday for Pt Arena to Pt Reyes 10-60 NM.
