A record-breaking heatwave has struck the southwestern United States, with an Arizona desert town near Martinez Lake setting a new national high for March temperatures at 110°F (43.3°C). This surpasses the previous record of 108°F (42.2°C) set in Texas in 1954. The extreme heat is part of a broader regional heatwave affecting major cities like Phoenix, San Diego, Los Angeles, Las Vegas, and San Francisco, many of which are experiencing record highs for this time of year. Phoenix, in particular, recorded its earliest triple-digit temperature in March.