I have beaten the game and the season is the same, so if you go to island 4 it will be winter, and since the breeders and the flyiers show up on island 4 I highly recommend leaving the game fairly afk till spring.
The seasons do change so stay where you are till spring. The ONLY exception is you could maybe go back to island 1 to clear that up. A full sack of coin should make it fairly easy to survive there. You also can destroy the mountain portal and it will slowly rebuild itself, but it gives you a bit of a break from attacks. You can use that time to send your farmers to that berry patch safely.
