The US is most popular with travellers during the summer, but this is when American families pack everything up and head out to visit Aunt Tilly. To avoid mobs (especially throughout the national park system), it's better to go during autumn or early spring.

Weather

The climate is temperate in most of the US. Generally, it gets hotter the further south you go and seasonally more extreme the further you are north and inland from the coasts. Winters in the northeast and upper Midwest can bring long periods below freezing even though it's still warm enough to swim at the beaches in Florida and southern California.