My local weather forecasters are underscoring that we are in a record-breaking heat wave right now. We expect the record for consecutive 90 degree plus daily highs for this time of the year as we head into Memorial Day. Yes, there have been above normal temperatures across the United States this year; still, climatologist John Christy, from the University of Alabama in Huntsville, explains:

We see hot and cold spots over the globe every month, and this was just our turn. Weather systems aligned in March in a way that changed normal circulation patterns and brought more warm air than usual to the continental U.S.

He and other climatologists point out that normal weather patterns like La Nina have been responsible. Although a warmer March for the lower 48 states, it was cool for Alaska, Australia, and parts of Russia. Globally, it was the coolest March in 13 years, but still warmer than the 20th century average. Based on 30 years of satellite measurements of the earth's surface air temperature, Dr. Christy calculated that March was one-fifth of 1 degree Fahrenheit warmer than usual.