A dangerous heat wave broke March temperature records across the southwestern United States this week, with Arizona recording 110 degrees Fahrenheit on Thursday - the highest March temperature ever recorded in the country. Multiple sites in Arizona and southern California reached preliminary readings of 109°F, which would mark the hottest March day on record for the United States.

Scientists from World Weather Attribution, an international research group, concluded in a preliminary analysis that the extreme temperatures would have been "virtually impossible without human-induced climate change." The study found that climate warming added between 4.7 to 7.2 degrees Fahrenheit to the temperatures experienced during the heat wave.

The March heat wave joins a growing list of extreme weather events that scientists classify as unprecedented, including the 2021 Pacific Northwest heat dome, devastating floods in Pakistan in 2022, and recent destructive hurricanes. Data from the National Oceanic and Atmospheric Administration shows the area of the United States experiencing extreme weather has doubled in the past five years compared to 20 years ago.

Government disaster officials report increasing difficulty managing these extreme events. Craig Fugate, former director of the Federal Emergency Management Agency, noted that weather events consistently exceeded historical models and preparedness systems. The United States now breaks 77% more hot weather records than in the 1970s, according to an analysis of NOAA data.

The frequency and cost of billion-dollar weather disasters has also escalated significantly. NOAA and Climate Central data shows such disasters now occur twice as often as a decade ago and nearly four times more frequently than 30 years ago, with costs adjusted for inflation. Climate scientists warn that extreme weather events are becoming more intense and occurring at unusual times and locations, putting more communities at risk.