Mars 2026 the hottest in over a century in the United States, up to 44°C in Arizona

A historically hot March at the country level The United States experienced its warmest March ever recorded since the beginning of measurements. Nationally, the thermal anomaly exceeded +5°C compared to normal temperatures, a considerable deviation for a monthly average. This is also the strongest temperature anomaly ever observed in the United States since measurements began 132 years ago. In detail, thousands of records were broken: over 19,000 daily records and about 2,000 monthly records. This episode is not limited to a few regions; it affects a large part of the territory, from the Southwest to the Great Plains, with a progressive extension towards the east.

Heat worthy of an early summer in the middle of March Temperatures reached unprecedented levels for the season. In the west and southwest, some stations recorded up to 44°C, an absolute record for the month of March in the United States. In many cities, temperatures were 10 to 17°C above normal, often comparable to early summer levels. This early heat was due to a powerful heat dome associated with an abnormally intense high-pressure ridge over the American Southwest.

Consequences visible on the environment The effects of this episode were immediate. In the western part of the country, snowfall is now very deficient, compromising water resources for the coming months. This situation is even more concerning as it accompanies a marked drought: nearly 60% of the territory is affected, with direct impacts on agriculture and water resources. Another notable consequence is a spectacular advancement of spring. In some regions, vegetation is up to a month ahead, exposing crops to increased risk in case of late frosts.

A strong signal of climate change According to NOAA experts, such an event would be nearly impossible today without human-induced climate change. This March is part of a series of recent records: the period from April 2025 to March 2026 is now the hottest ever recorded in the United States. This could be compounded in the coming months by the development of a potentially strong El Niño episode, which could further amplify thermal anomalies globally.