Horton gets a beating from the seasons when he's in the jungle. Just like everything else in the book, they seem to be attacking him. In fact, time passes slowly and rhythmically: "And soon it was Autumn" (62), "And then came the winter" (63), "And then came the springtime" (74). Dun dun dun.
Dun dun dun is right. The foreboding imagery, including rain, thunder and lightning, blowing leaves, and even "snow and sleet!" (63) foreshadows Horton's mean ol' friends, the sneaky hunters, and the nasty circus crowds.
When Horton reaches the U.S., all talk of weather and seasons comes to a halt. What's that all about? Is it because Horton is outside his natural habitat?