Temperatures in the lower 48 states were 8.6 degrees above normal for March and 6 degrees higher than average for the first three months of the year, according to calculations by the National Oceanic and Atmospheric Administration. That far exceeds the old records. The magnitude of how unusual the year has been in the U.S. has alarmed some meteorologists who have warned about global warming. One climate scientist said it’s the weather equivalent of a baseball player on steroids.