Unseasonal heat in March 2026 broke records in Arizona, California, and Mexico, as modeled data shows temperatures soaring above 100 degrees Fahrenheit.
On March 20, 2026, the first day of spring in the Northern Hemisphere brought summer-like conditions to the US Southwest, with extreme heat causing numerous record highs.
Temperatures in Yuma, Arizona, reached 109 degrees Fahrenheit, 28 degrees above the 1991-2020 average for that date, according to the National Weather Service.
Record Highs Across Regions
Four locations in Arizona and California, including near Yuma and Martinez Lake, tied for the highest US temperatures that day at 112 degrees Fahrenheit, as confirmed by weather station measurements.
In Texas, cities like Lubbock saw temperatures in the mid to upper 90s during late March, extending the heat wave's reach.
Mexico also experienced the swelter, with Hermosillo setting a new March record at 108 degrees Fahrenheit, based on news reports from that period.
The heat resulted from a strong high-pressure system that kept skies clear and air dry over the US and Mexico for more than a week, similar to summer conditions noted by the National Weather Service.
Forecasts indicated the heat would spread eastward into the US Midwest and Southeast by the following week, according to available data from NASA models.
