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.

The record high for March is 93 F (34 C), set back in 2022, he said.

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

Mark Reeves was heeding the advice, drinking plenty of water, staying in the shade and occasionally dipping into the many air-conditioned casinos. The visitor from New Zealand, who was standing in front of the famous Fountains of Bellagio, said he didn't think it would be this hot.

The heat hasn’t dampened his trip, however.

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

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. The message from park officials: Avoid strenuous hiking during the hottest part of the day, which they identify as 10 a.m. to 4 p.m.

At White Sands National Park in southern New Mexico, park officials were bracing for Spring Break crowds and urging people in social media posts to check the forecast before heading out. High temperatures could reach the mid 90s F (around 35 C).

In Colorado, the heat wave comes at the end of an unusually warm winter that 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.

Now, with temperatures forecast to climb even higher into the 80s this week, they’re urging people not to be tempted to turn on their sprinklers since the reduced water supply must stretch through summer. Utilities normally urge Colorado homeowners to wait until May to turn on the spigot.

Shonnie Cline, a spokesperson for Aurora Water, which provides water to 400,000 people in suburban Denver, said it’s possible temperatures could still drop below freezing later, causing any water left in sprinkler systems to freeze and break the lines.

“The sooner you wake it up, it’s not necessarily better,” she said of lawns.

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Associated Press journalists Jessica Hill in Las Vegas, Colleen Slevin in Denver and Susan Montoya Bryan in Albuquerque, New Mexico contributed to this report.