Depending on the type of climate you have in your area, dog flea season may range anytime from early spring to late autumn. In general, the worst of the flea season usually lasts from late spring all throughout summer, especially if it’s very hot and humid.
Flea eggs and larvae usually need temperatures between 70 and 85 degrees Fahrenheit for optimal development. So if you live in the Southern States, you might be unlucky to have an unusually long flea season, especially if the humidity is high (fleas need about 70 percent humidity).