The best pricing can be found in the month of March. Prices to Harlingen from Rapid City average $286. You can even find prices in March for less than $286, as users have found deals to Harlingen from as low as $128. The month of June appears to be one of the more expensive times to travel to Harlingen from Rapid City. Flying in the targeted month can save you up to 62%.
Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Rapid City to Harlingen as you normally would.