Issued at 1016 AM PDT Mon Mar 16 2026
The forecast remains on track this morning with the long duration Heat Advisory having gone into effect at 10AM PDT. This is the earliest and first Heat Advisory that we've issued in March for our office. While we continue to message the risks and compounding impacts of a heat wave, we want to also recognize that this is occurring during the week of most schools Spring Break. On top of regular visitors to the coastline, we'll have many more out of town or first time visitors. Water temperatures are mostly still in the 50s, cold water shock is a very real risk, so be careful out there! Also, we're keeping an eye on increasing southerly swell that may necessitate a Beach Hazard Statement at some point this week. Stay cool as cool as you can this week.
, Issued at 1225 AM PDT Mon Mar 16 2026 (Today and tonight)
After building for the last couple days, the much anticipated heat wave arrives in earnest today. A remarkably strong ridge of high pressure over the far eastern Pacific is meandering towards the coast this morning. This ridge has taken over the pattern and will be the primary driver of the heat wave this week. The early measurements on the strength of this ridge are coming in as expected. The 00Z sounding found an 850 mb temperature of 17.15C. That breaks the daily record of 16.8C. Similarly the 500 mb height was measured at 5880m, breaking the old daily record of 5860m. As the ridge continues to build and move closer over the next 24-36 hours, these benchmark values will only increase. Ensembles show a high likelihood that the 850 temp will reach 20C and the 500 mb height will reach 5900m by the 12Z sounding Tuesday. Those would both set monthly records by a wide margin, and are more typical of early August.
This translates to temperatures in the mid to upper 80s across the interior, and 70s along the coast today. The marine layer is still hanging on, but it is being compressed to 500 feet or lower under the high pressure. This keeps the marine influence very localized to the coast. Ocean Beach will feel a nice marine breeze, but don't expect it to reach over the hill.
Offshore winds have become established and will be moderate at times before the ridge moves firmly overhead Tuesday and winds calm. Hot weather combined with dry offshore winds requires taking a look at fire weather conditions, and for good reason. At 10:50 AM Sunday, Mt. St. Helena reported sustained 42 mph ENE winds with 7% relative humidity. We should see something similar later this morning. That would be a slam dunk Red Flag Warning in the Summer. The reason we are holding off is the live fuel moisture content. Fortunately it's March. The hills are still green and will not be receptive to burn. Live fuel moisture reaches its highest levels in Spring due to peak growing season. Dead fuel moisture, on the other hand, will respond more to the hot dry weather, and the Energy Release Component is expected to set monthly records this week. After the winds die down today, the next period of concern is when the ridge breaks down sometime around next weekend. This brings the potential for strong winds after all the fuel drying has occurred. As always, be cautious with campfires or any other potential ignition source.
..issued at 1225 AM PDT Mon Mar 16 2026 (Tuesday through Sunday)
After several days of this heat wave building, it will reach the top of the plateau by Tuesday. Interior temperatures will reach the low to mid 90s, with 70s and 80s along the coast. Wednesday through Friday look nearly identical. Hot spots this week include the southern Salinas Valley and Gabilan Range. There is a strong possibility that Pinnacles National Park records the earliest 100 degree day of the year this week. The current record for March is only 93. Along the coast the hot spot looks to be Santa Cruz, where downslope winds will add adiabatic heating to battle any marine influence. We expect low 90s there.
Numerous monthly records are expected to be broken this week. Check out the Climate section below for those benchmarks. Overall the big story with this heat wave is how early it is. Yes we've seen much hotter days in the Summer and early Fall, but we are a full 30 degrees warmer than normal this week. That's very unusual any time of year.
Finally, when will it end? All ensemble clusters agree that the ridge will start to weaken this weekend. That doesn't mean temperatures will drop all the way back to normal, but we should see a cooling trend of about 5 degrees per day from Saturday through Monday, effectively ending the heat wave.
(18z TAFS) Issued at 1032 AM PDT Mon Mar 16 2026
Widespread VFR conditions expected across the entire region through the TAF period. Only exception is potential for lower (MVFR) visibilities near the coast due to haze and/or sea spray. West- northwest winds will increase by early afternoon and linger into the evening as onshore flow returns to the region. Winds diminish overnight and become variable into early Tuesday morning.
Vicinity of SFO, VFR through the TAF period. A moderate west- northwest wind will increase a bit this afternoon before diminishing overnight and into early Tuesday morning.
SFO Bridge Approach, Similar to SFO.
Monterey Bay Terminals, VFR through the TAF period. A gentle to moderate west-northwest wind will increase a bit this afternoon before diminishing this evening and become variable into Tuesday morning. Winds may turn more southerly early Tuesday morning at KSNS.
(today through Saturday) Issued at 1016 AM PDT Mon Mar 16 2026
Breezy to gusty north winds linger in the northern outer waters through the day before easing tonight and into Tuesday morning. Winds across the waters continue to diminish through the work week. Sea heights remain moderate due to a combination of wind waves and low southerly swell.
Ca, Heat Advisory until 8 PM PDT Friday for CAZ006-502>506-508>510- 512>518-528>530.
PZ, Small Craft Advisory until 3 AM PDT Tuesday for Pt Arena to Pt Reyes 10-60 NM.
