These maps show the number of days per year in 10°F temperatures. For example, the map titled "Days With a High Temp in the 90°Fs" represents the average number of days with a high temperature between 90°F and 99°F - NOT 90°F AND ABOVE. This last part tends to cause a lot of confusion. Any number of people have made maps of days with a high of 90°F or greater, but these are the first maps that slice it into 10°F segments.