Prolonged March heat wave grips Western US cities

Temperatures soar to record highs in San Francisco, Las Vegas, and other areas

Mar. 18, 2026 at 5:18pm

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A rare and prolonged heat wave is gripping cities across the Western United States, with San Francisco, Las Vegas, and other areas experiencing record-breaking March temperatures. The hot, dry conditions are in stark contrast to the snow storms impacting the Midwest and eastern parts of the country.

Why it matters

This early and intense heat wave is highly unusual for this time of year, raising concerns about the impacts on water supplies, public health, and the ability of residents to cope with the high temperatures, especially in cities like San Francisco that are not as accustomed to extreme heat.

The details

San Francisco is seeing temperatures near 90°F, which is highly unusual for March. Las Vegas has a chance of reaching 100°F this weekend, which would be the earliest the city has ever hit triple digits. Other Western cities like Denver and Phoenix are also experiencing record-breaking March heat. The heat is straining water supplies, with some areas already enacting lawn watering restrictions.

  • On Tuesday, temperatures in San Francisco looked to tie the record high of 87°F set in 2005.
  • Las Vegas could reach 100°F on Saturday, which would be the earliest the city has ever hit triple digits.
  • Denver hasn't seen three consecutive March days above 80°F since 1907, but that could happen this week.

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

“We have our fans going, our windows open, but we try to be outside as much as we can.”

— Jessica Ling, San Francisco resident

“If people are visiting Vegas this weekend, they just need to prepare for the heat, make sure they're hydrating. This is going to be unusual for this time of year.”

— Brian Planz, Meteorologist

“For me, this is the trip of a lifetime. I've never been to the USA before and I may never get here again.”

— Mark Reeves

What’s next

Water providers in the Denver area are already enacting or considering limits on the number of days people can water their lawns, urging residents not to turn on sprinklers too early in the season.

The takeaway

This prolonged and intense March heat wave in the Western US is highly unusual and raises concerns about the impacts on water supplies, public health, and the ability of residents to cope, especially in cities like San Francisco that are not as accustomed to extreme heat this early in the year.