March 2026 Warmest on Record for Contiguous US

March 2026 marked the warmest March on record for the contiguous United States, with average temperatures across the Lower 48 states reaching 50.85 degrees Fahrenheit, according to the National Oceanic and Atmospheric Administration. This figure exceeded the 20th-century average by 9.35 degrees, surpassing the previous record set in March 2012 and establishing the month as the most abnormally hot in 132 years of national data.

The extreme warmth stemmed from a persistent high-pressure ridge, or heat dome, that dominated the Desert Southwest and Central Plains from mid-March onward, pushing temperatures into triple digits in parts of Arizona and Southern California. Ten western states—Arizona, California, Colorado, Idaho, Nevada, New Mexico, Oklahoma, Texas, Utah and Wyoming—recorded their hottest March averages on record. Broader regions, including the Ohio Valley and Southeast, also saw above-average temperatures, while nearly 500 counties, representing about one-quarter of the contiguous U.S., logged their highest March averages. No contiguous state experienced below-average temperatures, a rarity underscoring the event's scope.

The heat wave shattered thousands of temperature...