In most parts of the United States, temperatures must be above the historical average in an area for two or more days before the label "heat wave" is applied.
The summer of 2023 is shaping up to be a hot one. Most of the United States can expect a summer with above normal temperatures, according to the National Oceanic and Atmospheric Administration's seasonal outlook. Already the extreme heat and humidity that has been stifling Texas will linger there for much of this week, before it spreads into parts of the Southwest…