The National Climatic Data Center just released a map that shows when the hottest day of the year occurs throughout the country. The map was created using long term averages and shows some really interesting information.
For example, most of the hottest days occur after the summer solstice; meaning longer days does not necessarily mean hotter days. This occurs because there is a lag between the radiation from the sun on the solstice and when the atmosphere is actually warmed by this radiation.
Most of the country has likely made it through the hottest part of their summers. The Southwest experiences their hottest day in mid-June, and experiences more rain and thunderstorms in July due to the North American Monsoon.
Much of the Midwest, East Coast, and Central Rockies experience their hottest day in the middle of July. The south often sees its warmest days in August, and the west coast lags behind until September and even later in some more complicated cases. Alaska sees its peak in late July and early August, while Hawaii takes on the heat in September due to its tropical location.
After This Weekend is it all downhill from here? Most of the Eastern U.S. has peaked for their average daily max temps. Winter is on its way, and if you are like me, I will take it right about now. – Tom Niziol, The Weather Channel
We saw some interesting anomalies in June of this summer. The southwest had its second warmest June on record, second only to last year. Also, 34% Hawaii now faces a drought.
The southeast trended differently and experienced cooler temperatures and above average precipitation. All the data gathered shows a changing climate with new conditions in each area.