A Hot Start to Spring in the Southwest

Dark red spanning several southwestern U.S. states and part of Mexico indicating where the region’s saw the highest temperatures.

Extreme heat lingers over the U.S. Southwest and Mexico on March 20, 2026, in this visualization based on GEOS-FP data.

NASA Earth Observatory/Michala Garrison

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 that day amid a bout of extreme heat.

The extent and severity of the heat are represented on this map, which shows air temperatures on the afternoon of March 20, modeled at 2 meters (6.5 feet) above the ground. It was produced with a version of the GEOS (Goddard Earth Observing System) model, which integrates meteorological observations with mathematical equations that represent physical processes in the atmosphere. The darkest reds are where the model indicates 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. According to the National Weather Service (NWS), 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. In Texas, Lubbock experienced several days in the mid to upper 90s. Sweltering temperatures extended into Mexico as well. A new March record was set in Hermosillo, for example, where temperatures reached 108°F (42°C), according to news reports.

The heat was driven by a persistent high-pressure system, which the NWS noted was similar in strength to conditions seen in summer. It 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.

NASA Earth Observatory image by Michala Garrison, using GEOS-FP data from the Global Modeling and Assimilation Office at NASA GSFC. Story by Kathryn Hansen.