Bay Area/ San Francisco

Bay Area Braces for Sweltering Heat and Dense Fog with Multiple Advisories Issued by National Weather Service

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Published on May 31, 2025
Bay Area Braces for Sweltering Heat and Dense Fog with Multiple Advisories Issued by National Weather ServiceSource: Two+two=4, CC BY-SA 3.0, via Wikimedia Commons

The National Weather Service has issued a Heat Advisory for parts of the Bay Area as temperatures are expected to rise significantly. The advisory is in place from 11 AM to 8 PM this evening for select regions, including the Santa Clara Valley. In addition, a Dense Fog Advisory has been announced, spanning from San Mateo County to Monterey County, effective until 10 AM today. If you're driving through these areas, it's advised to remain cautious as the fog could drastically reduce visibility to less than half a mile at times.

With moderate HeatRisk anticipated in the interior locales, the National Weather Service in San Francisco urges residents to stay cool and hydrated during the sweltering temperatures, which could see highs reaching up to 100 degrees in some far interior spots. This heat wave comes alongside elevated fire weather concerns, owing to low relative humidity values and poor overnight recovery in higher terrains. The public should be vigilant and avoid activities that could ignite a grass fire. In light of the current conditions, NWS has recommended taking precautionary steps to prevent heat-related illnesses.

According to the NWS San Francisco report, a change in weather patterns is expected to begin on Sunday, leading to a cooldown with more seasonal temperatures forecast for the upcoming week. The marine layer, a crucial factor in moderating the regional climate, is set to return, bringing fog and the potential for coastal drizzle. As the heat pressure subsides, temperatures are anticipated to align with the seasonal norms gradually.

Meanwhile, the marine forecast projects rough seas over the next few days for those headed out onto the waters. A Gale Warning has been implemented for certain sectors, which could see strong gusts and waves escalating up to 22 feet in the northern coastal regions. Officials advise small craft operators to exercise extreme caution or avoid sailing during this period. As "gale force gusts are expected over the northern coastal waters," according to the NWS advisory, boaters must navigate these challenging conditions deftly.