The first official day of the Northern Hemisphere's spring in March 2026 felt more like summer across much of the southwestern United States. Numerous high-temperature records fell on March 20, 2026 amid a bout of extreme heat. Phoenix has never hit 100 degrees before March 26 in 137 years of record-keeping.
A map shows air temperatures on the afternoon of March 20, 2026, modeled at 2 meters above the ground using the GEOS model. The darkest reds on the map indicate temperatures reaching or exceeding 104 degrees Fahrenheit (40 degrees Celsius). Measurements from weather stations on March 20 pinpointed some of the highest U.S. temperatures in Arizona and California. Yuma, Arizona reached a record high of 109°F on March 20, 2026, which is 28 degrees above the 1991-2020 climatological normal for that date. Four other locations—near Yuma and Martinez Lake in Arizona and Ogilby and Winterhaven in California—tied for the highest temperatures in the U.S. on March 20, 2026, reaching 112°F (44°C).
Several other U.S. states saw temperatures soar in late March 2026, including Texas where Lubbock experienced several days in the mid to upper 90s. Sweltering temperatures extended into Mexico in late March 2026. A new March record was set in Hermosillo, Mexico, where temperatures reached 108°F (42°C). The heat was driven by a persistent high-pressure system, which the NWS noted was similar in strength to conditions seen in summer. The high-pressure system remained over the region for more than a week, keeping the air dry and skies clear across a vast stretch of the U.S. and Mexico. The heat dome baking the Southwest is creeping eastward and may be one of the most expansive heat waves in American history.
March 2024 was the hottest March on record for the US and the most abnormally hot month in 132 years of records. March’s average temperature was 10.47°C (50.85°F), 5.19°C (9.35°F) above the 20th-century normal, eclipsing the previous record from March 2012. More than 61% of the Lower 48 states is in moderate to exceptional drought, the highest for this time of year since the drought monitor began in 2000. The Palmer Drought Severity Index hit its highest level for March since records started in 1895, and last month was the third-driest month recorded. More than 19,800 daily temperature records were broken for heat across the country in March.
The heat was expected to spread east into the U.S. Midwest and Southeast by the following week. A potentially record-shattering spring heatwave is sweeping across the US East Coast, with temperatures forecasted to reach the mid-90s. Wednesday's highs in New York City, Philadelphia, Washington, Providence, and Raleigh are predicted to soar more than 20 degrees above seasonal norms. The National Weather Service projects a high around 86°F for Central Park in New York City on Wednesday, near the record of 87°F from 1941. A long-lasting weather pattern is poised to blast hot air across the eastern US, threatening to shatter record high temperatures on Wednesday. The Southwest will soon bake with day after day of record 100-degree-plus (38 Celsius-plus) heat.
Temperatures could reach 107 degrees in Phoenix, Arizona, and rare 90-degree March heat in Los Angeles. Some forecasts see 98 F (almost 37 C) in Phoenix on Tuesday, followed by 103, 105 and two days of 107 (almost 42 C). It has already started in Los Angeles, with unusual 90-degree March weather that had people in shorts and tank tops seeking shade. A heat dome will form early next week and park over the Southwest, baking temperatures to triple digits that haven't been seen this early in the year.
Extreme heat is already creating 'non-survivable' conditions for humans in heatwaves, according to new research. Heatwaves in Mecca (2024), Bangkok (2024), Phoenix (2023), Mount Isa (2019), Larkana (2015), and Seville (2003) had thousands of deaths despite not approaching the wet bulb limit of 35C. When applying a new model accounting for age and body function, all six heatwaves had non-survivable periods for older people in full sun. The weather service warned that since we are not acclimated to this level of heat this early in the year, it will be more impactful than usual.
Americans in every state have been warned to brace for extreme weather, including heat in the Southwest and a polar vortex in the Midwest and East. Winter temperatures are coming back for 100 million Americans as an icy, deep freeze takes over from the record-breaking heatwave. The polar vortex will again invade the Midwest and East with soul-crushing Arctic chill. Two storms will dump snow by the foot over northern Great Lakes states. Around the same time as the heat starts blasting Phoenix, the polar vortex is forecast to send its chill deep into the Midwest and East, even bordering some of the Southeast. Minneapolis will hover around zero (-18 C) for a low, and Chicago will be in the single digits Tuesday, with temperatures in the teens and 20s in the Northeast and 20s in the Mid-Atlantic the next day, and even Atlanta could drop to the 20s. Two storm systems in a row — one Friday, then another Sunday — will dump snow.
Weather whiplash has already hit much of the East, with Washington, D.C., residents walking around in shorts in record-breaking 86 degrees Fahrenheit (about 30 C) on Wednesday and it snowing on Thursday. Nearly every part of the United States is getting walloped by wild weather or just about to be.
Shoreline stations in California have measured record-breaking daily high water temperatures, with La Jolla station registering 10°F above historical average. The marine heatwave in southern California is compared to 'the Blob' from a decade ago, with potential devastating impacts on marine life. A new study found marine heat waves supercharge damage caused by hurricanes and tropical cyclones globally.
Snow surveys across the American West show record-low snowpack levels after a historically warm winter and searing March temperatures. Snow water equivalent (SWE) in California's Sierra Nevada was 4.9 inches, or 18% of average, as of Monday ahead of the April 1 survey. Snow water equivalent in the Colorado River headwaters was just over 4 inches, or 24% of average, less than half the previous record low. The Great Basin had 16% of average SWE, the lower Colorado region 10%, and the Rio Grande 8% on Monday.
Forecasts suggest a brewing El Nino could reach 'superstrength,' further intensifying global warmth. The Great Flood of 1862 dropped a record-setting amount of rain along the U.S. West Coast from December 1861 through January 1862. California was hit especially hard by the Great Flood of 1862, with San Francisco and Sacramento recording 34 and 37 inches of rain respectively over two months.
The NOAA-CIRES-DOE Twentieth Century Reanalysis (20CR) project has generated a four-dimensional global atmospheric dataset of weather spanning 1806 to 2015. The 20CR project uses a state-of-the-art data assimilation system and surface pressure observations to produce reanalyses. The earliest reanalyses before the 20CR project began in 1948, leaving out many important 20th century climate events like the 1930's Dust Bowl. The 20CR project is led by NOAA's Physical Sciences Laboratory (PSL) and CIRES at the University of Colorado, supported by the Department of Energy. The 20CR reanalyses assimilate only surface observations of synoptic pressure into NOAA's Global Forecast System and prescribe sea surface temperature and sea ice distribution. The 20CR project estimates temperature, pressure, winds, moisture, solar radiation, and clouds from the surface to the top of the atmosphere throughout the 19th and 20th centuries. 20CR uses an ensemble filter data assimilation method to estimate the most likely state of the global atmosphere for each three-hour period and its uncertainty. The most recent version of the 20CR reanalysis, V3, provides 8-times daily estimates of global tropospheric variability across 75 km grids, spanning 1836 to 2015, with an experimental extension from 1806 to 1835. There are three previous versions of the 20CR reanalysis: V1, V2, and V2c. Version V2c covers 1851-2012 with an experimental 2013-2014 extension. The 20CR project has benefited from international cooperation under the Atmospheric Circulation Reconstructions over the Earth (ACRE) initiative. The ACRE initiative recovers historical instrumental surface terrestrial and marine global weather observations to underpin 4D weather reconstructions spanning the last 200 to 250 years. Additional support for the 20CR project has been provided by the Global Climate Observing System and the World Climate Research Programme.
Several key unknowns remain as this extreme weather event unfolds. The specific dates in March or April 2026 being referred to for the extreme heat events remain unclear, as sources mention different times including March 20, 2026, March 2024, and April highs. How many people have been directly affected or injured by the extreme heat and cold events across the United States has not been confirmed. What specific measures are being taken by authorities to mitigate the impacts of the heatwaves, low snowpack, and drought on water supply and public health is not detailed in available reports. Whether the forecasted polar vortex and snowstorms will overlap with the heatwaves in any regions, creating simultaneous extreme weather conditions, remains uncertain. The exact economic costs or damages from the current extreme weather events, including impacts on agriculture, infrastructure, and energy systems, have not been quantified.