San Francisco Breaks March Temperature Record Amidst Unprecedented Heat Wave

San Francisco experienced an unprecedented heat wave, culminating in a record-breaking high of 90 degrees Fahrenheit on Friday, March 20, 2026. This shattered the previous all-time March record of 87 degrees set in 2005 and marks the city’s earliest 90-degree reading on record by more than two weeks. The heat wave is now subsiding, with a significant cooldown expected over the weekend.

Record-Breaking Heat

The temperature was recorded at the downtown weather station, located on Mint Hill near Duboce Park, just before 4 p.m. On Friday . At the same time, temperatures across the Bay Area ranged from the mid-80s to low 90s, a staggering 20 to 30 degrees above normal.

Cooling Trend Expected

A cooldown is already underway as the ridge of high pressure responsible for the heat flattens and the marine layer returns. San Francisco’s forecast high of 74 degrees on Saturday is nearly 20 degrees cooler than Friday’s peak. Temperatures across the region will be in the 70s and 80s on Saturday, with a further drop on Sunday, with much of the region seeing temperatures in the 60s .

Ongoing Hazards and Advisories

A Heat Advisory was in effect until 8:00 PM PDT on March 20, 2026 . The National Weather Service is too monitoring extreme heat conditions in the broader Southwest and fire weather risks in the central U.S. . A Kona low is bringing heavy rainfall to Hawaii through Sunday.

Current Conditions (as of March 21, 2026)

As of 5:43 PM PDT on March 20, 2026, conditions in San Francisco Downtown (SFOC1) were as follows :

• Temperature: 78°F (26°C)
• Humidity: 34%
• Wind Speed: Not Available
• Barometer: Not Available
• Dewpoint: 48°F (9°C)
• Visibility: Not Available
• Heat Index: 78°F (26°C)