Due to multiple factors, expect to potentially pay more when booking in October. For low rates, November can be a great choice for travel to South Padre Island. Flights to South Padre Island from Spokane in November are about $403 on average during November, but can be found for as low as $202.
Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Spokane to South Padre Island as you normally would.