 In an overheated city of 13 million people, the real toll will be higher than that. North America experienced a rare double heat dome. It has happened before, but never with such new high temperatures. The hottest days ever were just recorded in Palm Springs and Las Vegas, Nevada. It was 120 degrees Fahrenheit in Las Vegas, or 48.8 C. That is not just a fraction higher, but a full 3 degrees Fahrenheit over the previous record.