Ask anyone for America's hottest state and they'll say Arizona. The yearly numbers say Florida. Both answers are hiding something true.
A state's yearly average mixes everything together: summer and winter, daytime and night. Arizona has ferociously hot summer days — but that is not the same as being hottest all year.
Basis: How an average works — grade-school math.
Arizona is not all desert. Its northern half sits high up on the Colorado Plateau, with mountains, pine forests and snowy winters. Those cold months pull the state's yearly average down.
Basis: U.S. geography: northern Arizona's high plateau and mountain forests.
Florida is low, flat and surrounded by warm ocean, and its air is humid. Humid air holds onto heat after sunset, so Florida's nights stay warm — it has America's warmest nights, too (check the quiz data).
Basis: This site's NOAA data: Florida also leads in average nightly low temperature.
Arizona still wins bragging rights for hot afternoons: it's right near the top for how much air conditioning a state needs in a year, even though its yearly average temperature isn't.
Basis: This site's NOAA data: Arizona ranks #2 in cooling need.
📊 Sources for the rankings mentioned in this note (links to the original data and retrieval dates) are on each quiz page below.