Date of the warmest day of the year in the US.
Following the first official day of summer, many areas in the United States are approaching their highest temperatures for the year. To give you a better idea of the warmest time of year for your area, NCDC has created a new “Warmest Day of the Year” map for the contiguous United States. The map is derived from the 1981–2010 U.S. Climate Normals, NCDC’s 30-year averages of climatological variables including the average high temperature for every day. From these values scientists can identify which day of the year, on average, has the highest maximum temperature, referred to here as the “warmest day.”