In March 2026, the first official day of the Northern Hemisphere’s spring 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. 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, 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. that day, reaching 112°F (44°C). Several other U.S. states saw temperatures soar in late March, with Lubbock, Texas, experiencing several days in the mid to upper 90s. Sweltering temperatures extended into Mexico as well, where a new March record was set in Hermosillo, for example, with temperatures reaching 108°F (42°C). The heat was driven by a persistent high-pressure system, which was similar in strength to conditions seen in summer. This 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 was expected to spread east into the U.S. Midwest and Southeast by the following week. A gigantic heat dome that baked the Southwest is creeping eastward and may be one of the most expansive heat waves in American history. Fourteen states have notched their hottest March day on record since this heat dome started. At least 479 weather stations broke records for March from Wednesday through Saturday. According to reports, March was the most abnormally hot month in 132 years of records for the US, with an average temperature 5.19C above the 20th-century normal. More than 19,800 daily temperature records were broken for heat across the country in March. A long-lasting weather pattern is poised to blast hot air across the eastern US, threatening to shatter record high temperatures on Wednesday in cities like New York, Philadelphia, and Washington, D.C. The National Weather Service projects a high around 86 degrees for Central Park in New York City on Wednesday, near the record of 87 from 1941. 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 will soar more than 20 degrees above seasonal norms. The predicted Wednesday high in New York of 88 degrees would be the hottest on this day since 1941. New York City and Philadelphia experienced all-time April highs this week at 90F and 93F, respectively. Temperatures could reach 107 degrees in Phoenix, Arizona, and 90-degree heat in Los Angeles in March. Phoenix has never hit 100 degrees before March 26 in 137 years of record-keeping.
Snowpack across the American West is at record-low levels due to a historically warm winter and searing March temperatures. California's Sierra Nevada had 4.9 inches of snow water equivalent (SWE), or 18% of average, as of Monday ahead of the April 1 survey. The Colorado River headwaters had just over 4 inches of SWE, 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. Drought in the contiguous US has reached record levels for this time of year, with over 61% in moderate to exceptional drought. The Palmer Drought Severity Index hit its highest level for March since records started in 1895, and March was the third-driest month recorded.
Extreme heat is already creating 'non-survivable' conditions for humans in heatwaves, particularly for older people. 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. The Larkana and Phoenix heatwaves included periods non-survivable for older people even in shade, and Larkana had a period deadly for people aged 18-35 in full sun. Heat is the No. 1 weather-related killer in the U.S.
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 returning for 100 million Americans, with an icy deep freeze taking over from the record-breaking heatwave. Nearly every part of the United States is getting walloped by wild weather or just about to be. The Southwest will soon bake with day after day of record 100-degree-plus (38 Celsius-plus) heat. Two storms will dump snow by the foot over northern Great Lakes states. The dreaded polar vortex will again invade the Midwest and East with soul-crushing Arctic chill. 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. 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. 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 wherever they could find it. 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 Atlanta could drop to the 20s. Two storm systems in a row — one Friday, then another Sunday — will dump snow.
A map shows air temperatures on the afternoon of March 20, modeled at 2 meters (6.5 feet) above the ground, produced with a version of the GEOS (Goddard Earth Observing System) model. The GEOS model integrates meteorological observations with mathematical equations that represent physical processes in the atmosphere. The darkest reds on the map are where the model indicates temperatures reaching or exceeding 104 degrees Fahrenheit (40 degrees Celsius).
Health impacts and mortality rates from the March 2026 heatwaves are not fully known. Effects of low snowpack and drought on water supply and wildfire risk remain uncertain. Specifics of forecasted polar vortex and cold snaps are still being monitored. Economic costs and emergency measures in response to extreme conditions are unclear.