It’s generally more expensive to depart on a Saturday, if you have to leave on this day you can still search on Cheapflights to find great options that meet your needs.
Due to multiple factors, expect to potentially pay more when booking in March. For low rates, September can be a great choice for travel to Belize City. Flights to Belize City from Rapid City in September are about $537 on average during September, but can be found for as low as $427.
A simple way to save on the total cost of your ticket is to fly from Rapid City to Belize City in the morning. If you’re flexible enough to do this you can expect to save up to 61% on your trip compared to booking a flight in the afternoon.