Dozens of cities from California to Colorado recorded their highest temperatures ever for the month of March, according to the National Weather Service Weather Prediction Center.
On Saturday, areas that saw new records for the highest temperatures in March included 92 Fahrenheit (33.3 °C) recorded in Kansas City, Missouri, and North Platte, Nebraska.
Topeka, the state capital of Kansas, broke its March record Saturday with a high of 95F (35 °C), weather officials said.
In Wyoming, the least populous US state, all-time March temperatures were set in capital Cheyenne at 83F (28.3 °C).
On top of the monthly all-time highs, the heatwave reached several other temperature milestones.
For instance, in Chanute, Kansas, temperatures went from a record low of 13F (-10.5 °C) on March 16 to a record high of 91F (32.8 °C) just four days later.
And in Phoenix, Arizona, one of the hottest cities in the United States, the daily low was a balmy 70F (21.1 °C) on Saturday, the earliest in the year such a level had been reached, the weather agency said.
Cities recording all-time daily highs Saturday included Denver (86F), Grand Island, Nebraska (98F) and Midland, Texas (98F).
On Friday the heatwave had brought temperatures up to 44.4 °C (112F) in several areas along the southern California-Arizona border, a national US record for March.
The National Weather Service issued an extreme heat warning for the same desert areas on Saturday, as well as a red flag warning — indicating high wildfire risk – for much of the central Plains states of Nebraska, Kansas and Oklahoma.
Scientists say there is overwhelming evidence that current heatwaves are a clear marker of global warming, a process driven chiefly by the burning of fossil fuels.
With winter in the northern hemisphere officially ending on Friday – the first day of astronomical spring – the soaring temperatures were wreaking havoc on wildlife in the West.
Many plants and trees are already blooming, and vegetation is growing at a fantastic clip, fueled by heavy rains in December and January.
