Unprecedented March Heatwave Sweeps Across the U.S. West

Wed Mar 18 2026 00:05:05 GMT+0000 (Coordinated Universal Time)

San Francisco experiences its hottest March temperatures in two decades as a heatwave affects many parts of the Western US, leading to record highs and extreme weather alerts.

San Francisco is experiencing its hottest March in over 20 years, with temperatures nearing 90°F, while neighboring cities like Phoenix and Las Vegas prepare for record-breaking highs exceeding 100°F. Amidst this unusual heatwave, many in the San Francisco Bay Area are enjoying the summer-like weather, although some are struggling without air conditioning. The Midwest and eastern regions are coping with heavy snowfall and related disruptions. Meteorologists confirm that such early heat extremes are rare but have occurred in the past, raising concerns about water supply in regions facing drought conditions.

SAN FRANCISCO (AP) — San Franciscans bared an unusual amount of skin for this time of year Tuesday, as a city better known for its chilly summers, drizzle, and fog is seeing its hottest March in at least two decades, part of a rare winter heat wave baking the U.S. West.

While the Bay Area flirts with nearly 90 degree (32.2 C) highs, Phoenix is expected to top 100 F (37.7 C) this week — something it usually does in early May and has never done before March 26 — and Las Vegas could also see its earliest ever triple-digit temperature in the coming days.

Meanwhile, the Midwest and eastern half of the country are digging out after powerful snow storms that led to thousands of flight cancellations this week.

Dogs and sunbathers flocked to Crissy Field on the north end of San Francisco, as the Golden Gate Bridge shimmered nearby.

“It feels like summer already in March. That’s crazy, but I love it,” said dog walker Justyce Roliz. “The dogs, they love running in the water. They love to cool off. They’re loving it.”

Resident Jessica Ling said the hot weather was a nice surprise, “but it’s difficult because we don’t have AC in our house. So we have our fans going, our windows open, but we try to be outside as much as we can.”

Records across the Bay Area toppled Monday and highs Tuesday were projected to climb even higher. San Francisco International Airport hit 83 F (28.3 C) Monday, while Silicon Valley’s Redwood City reached 90 F (32.2 C), breaking records set in 2004. San Jose reached 85 F (29.4 C), tying a record set in 1914.

It’s unusual for San Francisco to get this hot this early, but not unheard of, said Roger Gass, a meteorologist with the National Weather Service in the Bay Area. It last happened in 2005, when downtown hit a record 87 F (30.5 C) on March 11, part of a two-day heat wave and its record high for the month. In March 2004, the city saw a nearly week-long heat wave with temperatures around 80 F (26.7 C).

Las Vegas could reach between 94 and 98 F (34.4 and 36.6 C) over the next few days with a chance temperatures could reach 100 F (37.7 C) Saturday, said meteorologist Brian Planz at the city’s National Weather Service forecast office. That would be the earliest Las Vegas has reached triple digits.

Weather forecasters in Arizona issued extreme heat warnings for areas in Grand Canyon National Park from Wednesday through Sunday. They say temperatures could range from 96 to 104 F (35.5 to 40 C) in the lower elevations of the park, including Grand Canyon Village on the South Rim and Phantom Ranch down in the canyon.

In Colorado, the heat wave comes at the end of an unusually warm winter which has led to a lack of snow in the state’s mountains, which provides the water that millions of people depend on. Water providers in the Denver area have already enacted or are considering limits on the number of days people can water their lawns.