San Francisco Sees Rare Winter Heat Wave

Unusually warm temperatures hit the West, with records broken across the Bay Area.

Mar. 18, 2026 at 3:18am

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San Francisco is experiencing an unusual heat wave for this time of year, with temperatures reaching the high 80s Fahrenheit. This is part of a broader winter heat wave affecting the western United States, with Phoenix expected to top 100F and Las Vegas potentially reaching triple digits earlier than ever before. The warm weather has led to concerns about water supply in Colorado, where utilities are urging residents to hold off on turning on their sprinklers.

Why it matters

The extreme heat in San Francisco and other western cities is an unusual weather event, highlighting the impacts of climate change. The early arrival of high temperatures raises concerns about water scarcity and the ability of infrastructure and communities to adapt to more frequent extreme weather.

The details

San Francisco residents have been enjoying the unseasonably warm weather, with people flocking to beaches and parks. However, the lack of air conditioning in many homes has made the heat difficult to manage. Records have been broken across the Bay Area, with San Francisco International Airport hitting 83F on Monday and Redwood City reaching 90F. Similar high temperatures are expected in Las Vegas and Phoenix in the coming days, which would be the earliest the cities have ever reached those milestones.

  • On Monday, March 18, 2026, San Francisco International Airport hit 83F, breaking a record.
  • On Monday, March 18, 2026, Redwood City reached 90F, breaking a record.

The players

Roger Gass

A meteorologist with the National Weather Service in the Bay Area.

Brian Planz

A meteorologist at the National Weather Service forecast office in Las Vegas.

Shonnie Cline

A spokesperson for Aurora Water, which provides water to 400,000 people in suburban Denver.

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What they’re saying

“It feels like summer already in March. That's crazy, but I love it.”

— Justyce Roliz, Dog walker (ksgf.com)

“The heat hasn't dampened his trip, however.”

— Mark Reeves (ksgf.com)

What’s next

Utilities in the Denver area are considering limits on the number of days people can water their lawns due to concerns about water supply.

The takeaway

The extreme heat wave in the West highlights the growing impacts of climate change, with communities having to adapt to more frequent and severe weather events. The early arrival of high temperatures raises concerns about water scarcity and the ability of infrastructure to handle the strain.