I always wondered. Here its mild, its sweet; It havent got hot too much yet. but since USA is south of canada, i always wondered it must be hotter than here .
I'm in Arizona. This is really close to the hottest spot. America is probably mostly spring and summer weather now. The high altitudes are generally colder if they are in the mountains. The weather in Chicago is probably at least 40 degrees colder than here. AT LEAST; no mountains but it is further north and further east. So, everything makes a difference and this difference can make you really cold.
And certain months the whole nation experiences heat. But since we are a large mass of land with ups and downs and waterways etc., we have different temperatures. And then we have seasons in some parts meaning we have a spring summer winter and fall.
Where I am the winters are as warm as many people's springs are. Even summers.