Historic Heat Wave Set March US High, May Set Monthly Records In Over 140 Cities, From California To Missouri

Jonathan Erdman Sat, March 21, 2026 at 12:03 PM UTC

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A historic March heat wave has already smashed monthly records in dozens of cities in the West. This unusually early heat will spread into parts of the Plains and will have staying power in the Southwest into next week.

(MAP: Temperatures Right Now)

National March Record Set

Topping the list of most impressive heat records, so far, was one location in the desert of southwestern Arizona.

Thursday, a reporting station west of Martinez Lake, Arizona, recorded a high of 110 degrees.

This broke the nation's hottest March temperature record of 108 degrees, previously tied on Wednesday in North Shore, California. This record was initially set in Rio Grande City, Texas, on March 30, 1954, and on March 14, 1902.

This also appeared to top Arizona's March state record of 104 degrees in Yuma on March 21, 2004.

An ad hoc committee of meteorologists may examine this 110-degree high to confirm a new record at a later date.

March Records Already Set

So far, at least 65 cities have already tied or set new March record highs, from Arizona and California to southern Oregon, Idaho, Wyoming and New Mexico.

Phoenix set its all-time record high for March on Thursday with a temperature of 105 degrees — only the city's third 100-degree high in March on record. On Wednesday, the city saw its earliest triple-digit high at 102 degrees, eight days earlier than the previous record earliest triple-digit high (March 26, 1988).

Other March records set on Thursday included Las Vegas (95 degrees) and Santa Rosa (92 degrees), while Death Valley and San Francisco tied their all-time March records at 104 degrees and 85 degrees, respectively.

Redwood City, California, hit 90 degrees multiple days this week, when they hadn't previously reached 90 in March in 96 years of records.

It's so warm some male skiers and snowboarders were seen shirtless carving the slopes at Breckenridge, Colorado, Wednesday.

Michael Ciaglo/Getty ImagesHeat Wave's Peak Is Still Ahead

There's still more ahead in this heat wave.

The National Weather Service has issued extreme heat warnings and heat advisories in the Southwest, including Phoenix and Las Vegas.

(MORE: Heat Safety And Preparation)

It will not only intensify in the Southwest, but it will also spread throughout much of the West into parts of the Plains and South as we head into the weekend.

While some cooler air will slide into the northern and central U.S. beginning Sunday, record heat will persist in the Southwest into at least the first half of next week.

How hot are we talking about? Think mid-summer heat as we're turning the page officially to spring in mid-late March.

Triple-digit highs: The Desert Southwest, including Phoenix, Tucson, possibly as far north as Las Vegas, and parts of the L.A. Basin, are forecast to see 100-degree-plus highs for multiple days. This weekend, a few of the hottest locations in the Southern Plains could also reach the century mark.

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90s: California's Central Valley, even parts of the Bay Area, will rise into the 90s for multiple days. This weekend, 90s are possible as far north as Nebraska, Colorado and Kansas. And that could reach as far east as Omaha and Kansas City.

(MAPS: 10-Day US Forecast Highs, Lows)

Historic Notables

Again, we're not just talking about records set for a specific calendar day. This heat wave could set records for any March day in over 140 cities from California to Montana to South Dakota to Texas.

These are locations that could tie or set new all-time March heat records in this heat wave.

Prior to this, Phoenix, Arizona, had only hit 100 degrees once in March. They're expected to see triple-digit highs every day into at least this weekend, if not into much of next week. In an average year, they typically don't reach 100 degrees until May 2.

Both Las Vegas and downtown Los Angeles have never hit 100 degrees in March. They have a low chance of doing that in this heat wave.

Kansas City hasn't reached 90 degrees in March since 1910. They might do that this weekend. In parts of the Plains, highs this weekend could be as much as 45 degrees warmer than average.

Perhaps most impressive is some all-time March records for additional entire states could be in jeopardy. According to weather historian Christopher Burt, 13 additional states from Nevada to Iowa to Oklahoma could threaten their all-time state March records, including:

Nevada: 100 at Laughlin on March 17, 2007

Colorado: 96 at Holly on March 19, 1907

Iowa: 93 at multiple locations in 1986, 1910 and 1907

Missouri: 95 at Belle on March 21, 1907

Oklahoma: 104 at Frederick on March 27, 1971

Put simply, this may be the most significant, long-lived March heat wave the nation has experienced since the March 2012 heat wave rewrote the record books in the central U.S. and Canada.

Forecast Departures From Average High TemperaturesWhy So Hot So Soon?

The reason for this heat wave in particular has to do with the ridge of high pressure, also known as a heat dome, that is parked over the West.

This heat dome is record-breaking for March, comparable in strength to ones we see in June. You can see the general position of the high pressure on the graphic below.

Record high pressure? Record temperatures. Temperatures we are seeing this week... in March... are comparable to what we should be seeing in summer.

This heat dome will eventually weaken and flatten a bit later next week.

Snow Drought, Climate Change

The warmest winter on record in much of the West has already left snowpack at its lowest levels in at least two decades from the Rockies of Colorado to the Oregon Cascades.

As the graph below shows, Colorado's snowpack is at its lowest for any mid-March in the last 40 years, according to the USDA's National Water and Climate Center.

NRCS/USDA

After feet of snowfall in early February, California's Sierra snowpack has since dwindled to only 42% of average for this time of year, according to the California Department of Water Resources. Melting snow in spring and summer typically supplies 30% of the state's water. Fortunately, the state's reservoirs are higher than average due to recent wet years.

This heat wave will further deplete the already paltry snowpack in the West. That could lead to an expansion of drought in the Southwest and higher fire danger early this summer before the summer monsoon kicks in, according to outlooks by NOAA and the National Interagency Fire Center.

And this heat wave appears to have climate change's fingerprints on it.

According to an analysis by Climate Central, the magnitude of this heat wave by March standards has been made at least five times more likely by climate change.

Jonathan Erdman is a senior meteorologist at weather.com and has been covering national and international weather since 1996. Extreme and bizarre weather are his favorite topics. Reach out to him on Bluesky, X (formerly Twitter) and Facebook.

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