Issued at 841 AM PDT Tue Mar 17 2026
Good radiational cooling took place across the valleys this morning allowing temperatures to fall into the upper 40s to low 50s. However, the higher elevations remained warm and only cooled down into the 70s as the mid/upper level high pressure inches closer to the coast. As such, another very warm afternoon is in store across the Bay Area and Central Coast with a Heat Advisory in effect through 8 PM Friday. Northwest facing coastal areas will warm into the 80s the afternoon with upper 80s to low 90s across the interior and the Santa Cruz area. Please see the previous discussion below on records broken yesterday.
RGass
, Issued at 113 AM PDT Tue Mar 17 2026 (Today and tonight)
The heat wave is definitely here as a ridge settles over the western United States. Yesterday's 00Z (5 PM PDT) balloon from OAK reported a 500 mb height of 5911 meters, the highest reported height for the month of March and close to the mean height for early August. The 850 mb temperature of 20.4 C was also a record high for the month of March, more climatologically typical of the mid July to mid August period. Five stations across the region reported daily record highs, and Redwood City reported an all-time record high for the month of March.
Today will feature even warmer temperatures and the chances for more daily and potentially monthly record highs to fall, with highs in the upper 80s to middle 90s inland amd close to the Bays, while the Pacific coast hovers in the 70s. Lows this morning remain in the middle 50s to lower 60s in the lower elevations, with the thermal belts rather active as higher elevations see lows in the middle 60s to lower 70s. With the influence of the high pressure system right over the state, clear skies prevail and winds will remain light through the day.
Widespread Moderate HeatRisk is expected today, corresponding to a medium risk of heat-related illnesses for sensitive populations, including children, the elderly, pregnant women, people with chronic diseases, and people who live or work outside without adequate shelter or cooling. Given the abnormally hot conditions for the middle of March, a Heat Advisory remains in effect for the Bay Area and Central Coast today. Follow these tips to protect yourself, your loved ones, and your animals.
-Stay inside in an air conditioned environment between 10am and 7pm. -Suspend unnecessary outdoor activities during the extreme heat, but if you must be outdoors, take frequent breaks in the shade or AC and drink cool water. -Know the signs and symptoms of Heat Exhaustion vs. Heat Stroke! Heat Stroke can be deadly if not treated immediately by a medical professional. Call 911 if you suspect someone is suffering from Heat Stroke. -Wear a life vest, swim near a lifeguard, and check conditions before entering the water if going to a river or ocean to cool off. Rivers and the ocean are extremely cold, and Cold Water Shock can turn into paralysis and drowning if you are not careful. -Use a cool and damp towel on your body if you do not have AC and are feeling hot. Or, take a cool shower or bath. -Do not leave kids or pets in a parked car. -Ensure pets and livestock have access to shade and water.
..issued at 113 AM PDT Tue Mar 17 2026 (Wednesday through Monday)
Wednesday through Friday feature similar conditions to today, with temperatures far above the seasonal averages, widespread Moderate HeatRisk, sunny skies, and light winds as the associated upper level ridge crawls across California. A slight warming trend will continue with portions of the Central Coast, including the Ben Lomond-Boulder Creek area, the Morgan Hill-Hollister corridor, and the southern Salinas Valley, seeing temperatures rising into the upper 90s. A couple of favored patches will even see Major HeatRisk, corresponding to a high level of danger for heat-related illnesses for the general population. Notable regions for Major HeatRisk impacts include the ridgelines of the Santa Cruz Mountains, Carmel Valley, and the foothills of the Gabilan Range east of Salinas. The Heat Advisory in effect for the entire forecast region remains in place through Friday evening at the earliest.
For the upcoming weekend, the ridge begins to break down as it crawls eastwards across the Desert Southwest. This will give us a gradual cooling trend, but will also promote an strengthening pressure gradient, leading to stronger winds and an elevated risk for grass fires across the region. The extreme heat of the last few days will dry out a lot of fine fuels across the region, and pulses of offshore flow are possible Friday into the weekend, especially in the South Bay and Central Coast. There are a couple of mitigating factors. The first is that live fuels remain rather moist as the peak growing season continues. The second is that the larger scale pattern is for winds to remain onshore, especially in the North Bay. As for the temperatures, they will gradually cool around 5-10 degrees per day starting on Saturday, and by the early part of next week, temperatures might only be slightly higher than the seasonal averages.
(18z TAFS) Issued at 1059 AM PDT Tue Mar 17 2026
A few high clouds are passing over the region, with VFR conditions prevailing. Expect quiet weather and generally light winds to continue through the forecast period.
Vicinity of SFO, Winds will become onshore by this afternoon and should get up to 10kt before becoming light and variable or weakly offshore later this evening. VFR conditions will prevail.
SFO Bridge Approach, Similar to SFO.
Monterey Bay Terminals, Quiet weather continues with winds being a bit variable around the Monterey Bay. For KSNS and around KMRY, winds remain offshore this morning but will become onshore by the afternoon. The forecast will be on repeat for tonight, with offshore
(today through Sunday) Issued at 859 AM PDT Tue Mar 17 2026
Moderate NNW to N breezes will prevail offshore, with gentle breezes within 10NM. Seas are moderate from a combination of wind waves and a low southerly swell. Similar conditions will persist through Thursday before winds increase to a strong NNW breeze with rough seas from Friday through Sunday.
Ca, Heat Advisory until 8 PM PDT Friday for CAZ006-502>506-508>510- 512>518-528>530.
PZ, None.
