Due to multiple factors, expect to potentially pay more when booking in September. For low rates, July can be a great choice for travel to La Crosse. Flights to La Crosse from New York LaGuardia Airport in July are about $325 on average during July, but can be found for as low as $111.
Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from New York LaGuardia Airport to La Crosse as you normally would.