San Francisco, CA – A Heat Advisory is in effect Tuesday for the East Bay, San Francisco Bay shoreline, Santa Clara Valley, and San Francisco, with dangerously hot conditions expected to impact the region.
According to the National Weather Service, temperatures may reach up to 100 degrees in parts of the East Bay and rise into the mid-to-upper 90s across the San Francisco Bay shoreline and Santa Clara Valley. San Francisco itself could see highs in the upper 80s. The advisory will remain in place from 11 a.m. to 7 p.m. Tuesday, September 23, 2025.
Forecasters warn that these conditions bring a moderate heat risk, the second of four levels on the NWS scale. While most healthy adults can tolerate the heat, vulnerable groups such as older adults, infants, outdoor workers, and those with chronic illnesses face increased risks of heat-related illness.
The warmest period of the day is expected from late morning through mid-afternoon, with some relief possible later as onshore winds return. Officials emphasize hydration, recommending residents drink plenty of water, wear lightweight clothing, and avoid strenuous outdoor activity during peak heat.
The Occupational Safety and Health Administration advises outdoor workers to take frequent shaded breaks and schedule heavy labor for early morning or evening hours. Heat stroke is a medical emergency; anyone showing symptoms should be moved to a cool location and emergency services called.
Authorities also remind residents: never leave children or pets in vehicles, as interior temperatures can become lethal within minutes.
