Las Vegas sets new March record as historic heat spreads across the U.S. Southwest

A historic March heat event affected large parts of the U.S. Southwest on March 19 and 20, setting new temperature records across Nevada, California, and Arizona. The National Weather Service (NWS) said temperatures were running about 11 to 17°C (20 to 30°F) above average in parts of the region.

In Las Vegas, Nevada, Harry Reid International Airport reached 35°C (95°F) on March 19, setting a new March temperature record for the city. The new record came one day after Las Vegas tied its previous March high at 34.4°C (94°F).

Near Martinez Lake, Arizona, temperatures reached 43.3°C (110°F) on March 20, setting a new highest March temperature ever recorded in the United States. The previous U.S. March record was 42.2°C (108°F), set in Rio Grande City, Texas, in 1954 and later tied in California.

Phoenix, Arizona, reached 40.6°C (105°F), breaking its previous March record and marking the earliest triple-digit temperature recorded there in March in nearly four decades, according to AP.

Authorities in Phoenix restricted access to several popular hiking trails from March 19 to 22 because of dangerous heat conditions. The city said some trails would be closed or access-limited from 08:00 to 17:00 local time during the Extreme Heat Warning.

Elsewhere in the region, multiple stations reported new daily or monthly temperature records. The NWS described the event as a historic March heatwave affecting much of the Southwest.

A strong mid- to upper-level ridge is forecast to persist across the western and central United States through the weekend, supporting warm and dry conditions across much of the country.

The ongoing record-breaking heat in the West is expected to continue and expand into parts of the central United States. Temperatures are forecast to remain about 14 to 19°C (25 to 35°F) above average for this time of year, with numerous daily and monthly records likely to be challenged or broken.

Daytime highs are expected to reach the 32 to 38°C (90 to 100°F) range across the Southwest, the 27 to 31°C (80 to 88°F) range across the Intermountain West, and 21 to 35°C (70 to 95°F) across the Great Plains.

Overnight low temperatures are also forecast to remain well above average, limiting nighttime relief from the heat. The early-season timing, multi-day duration, and limited seasonal acclimatization are expected to increase the risk of heat-related impacts, especially for sensitive groups and people without access to effective cooling.

Residents are advised to limit strenuous outdoor activity to the early morning hours, stay hydrated, and seek air-conditioned spaces whenever possible.

In addition to the heat, parts of the northern and central High Plains are expected to face elevated to critical fire weather conditions through Saturday. Dry conditions, very low relative humidity, and strong downslope winds off the Rockies are expected to support extreme fire behavior and rapid fire spread.

Conditions may briefly improve on Sunday, but unfavorable fire weather is forecast to return early next week.

References:

¹ Record Event Report – NWS – March 19, 2026

² Record Event Report – NWS – March 20, 2026

³ Short Range Forecast Discussion – NWS – March 20, 2026