NWS Issues Unprecedented March Heat Advisory for Bay Area

Sunbathers descended on Dolores Park this week as the National Weather Service issued what forecasters are calling an unprecedented March heat advisory for the Bay Area, warning that temperatures climbing into the 80s and 90s this weekend and into next week could shatter monthly records across multiple cities.

The advisory, issued early Tuesday morning, March 10, predicts an extended stretch of above-normal heat beginning Wednesday, March 11, with conditions intensifying through the weekend and peaking early next week. Widespread minor heat risk is forecast from Wednesday through Saturday, escalating to moderate heat risk Sunday through at least Wednesday of next week.

"Next Tuesday will likely be the hottest day of the heat wave," said Brayden Murdock, a meteorologist with the National Weather Service's Bay Area office. "For us to see this heat wave early does make it a little bit more uncommon, and then the magnitude of some of the temperatures we're going to be seeing makes it pretty rare."

Inland areas are expected to climb into the mid-80s to lower 90s by early next week, while coastal zones will likely see highs in the 70s to mid-80s, according to the NWS advisory. The service characterized the pattern as "unusual weather patterns" bringing "summer-like heat to the Bay Area and Central Coast," adding that the event "will feel more like early August" than mid-March.

KRON4 meteorologist John Shrable put the stakes more starkly. "To say these temperatures are unprecedented is right," Shrable said. "March highs usually average out in the 60s for San Francisco and Oakland, both of which will likely break monthly temperature records next week. Even San Jose will likely see all-time March temperature records shattered as highs in the South Bay rise past the mid 90s come Tuesday."

The NWS pointed to an often-overlooked hazard of early-season heat: the body simply isn't ready for it. "Why are we worried about highs in the 80s and 90s?" the agency said. "Because this time of year, the body isn't used to dealing with this level of heat, so these highs are more impactful now than they would be in July." Forecasters specifically flagged elevated risk of heat-related illness for people sensitive to heat, as well as pets and livestock without adequate cooling or hydration.

Beyond public health, the heat wave threatens to rapidly melt the Sierra Nevada's snowpack, which is critical to California's water supply heading into summer. Murdock noted that Oakland and San José are among cities that could surpass their monthly high-temperature records, and that San Francisco could hit the 80s as soon as Sunday.