Fog City Sizzles: First Heat Spell Hits San Francisco As Tides Creep Higher

San Francisco started today wrapped in its usual cool marine layer, but it won't last long. Sunshine is taking over for the rest of the week, with inland valleys gearing up to roast later in the week and low-lying bayshore spots staring down minor flooding during high tide. Around the city, temperatures sit in the mid-50s this morning and are expected to top out in the mid-to-upper 70s today. A sharper warm-up arrives tomorrow. Beachgoers, shoreline drivers, and folks in the interior hills should keep a close eye on changing conditions.

What To Expect This Week

The sun takes the lead through Saturday. San Francisco highs should land near 77°F today and around 84°F tomorrow, while inland valleys climb into the 90s with some of the hottest pockets pushing into the triple digits. A Heat Advisory is scheduled for many inland and bayside neighborhoods from noon to 11 PM tomorrow, with forecasters warning of a moderate risk of heat-related illness for especially sensitive people.

Overnight lows in the city will mostly settle in the mid-to-upper 50s, while thermal belts and valley floors will stay warmer. According to the National Weather Service, anyone who has to be outside on Thursday should take frequent breaks and drink plenty of water.

Coastal Flooding And Beach Hazards

Minor coastal flooding could begin affecting low-lying bayshore spots this evening in parts of the North Bay, then spread to more of the San Francisco shoreline by tomorrow evening. The highest impacts are expected around high tides. Forecasters say the San Francisco tide gauge could run about 1 foot above normal tomorrow night and up to about 1.5 feet above normal Friday night. That would be enough to put water into some parking lots, parks, and low-lying roads.

A long-period southerly swell of about 4 to 6 ft with 19 to 21 second periods will also boost the risk of sneaker waves and strong rip currents on south- and southwest-facing beaches. The advice is simple: stay well back from the surf, keep a solid distance from wet and slippery rocks, and never turn your back on the ocean.

Fire Weather Concerns

Offshore overnight winds are expected to ramp up in the interior North and East Bay mountains tonight. Gusts could reach 35 to 45 mph, with isolated ridgetops flirting with gusts near 60 mph. Those conditions have prompted Red Flag Warnings for parts of the North Bay.

Poor overnight humidity recovery will keep vegetation dry, so any accidental spark could spread quickly between 11 PM today and 9 AM tomorrow. If you live or work in the hills, avoid open flames, use extreme caution with any equipment that might throw a spark, and keep it well away from dry brush and grasses.

How To Stay Safe

Tomorrow, try to skip strenuous outdoor activity during the warmest part of the day, drink water regularly, and check in on neighbors or family members who might be more vulnerable to the heat. If the heat inside your home is a concern, San Francisco Public Library branches and other locations can serve as cooling centers. You can find locations and hours on the San Francisco Public Library cooling centers page.

For shoreline neighborhoods, do not drive through flooded streets, and steer clear of beaches while advisories are in effect. Tie down or bring in loose outdoor items in windy areas. And as always, never leave pets in hot cars, even for a short stop.