To save up to 11% on this flight, we recommend booking at least 41 days prior to travel. The price may fluctuate and will likely increase closer to your departure date. Users on Cheapflights have found tickets from Kalispell to Puerto Rico from $380 1-2 weeks out and tickets from $415 for flights departing within the next 72 hours.
Due to multiple factors, expect to potentially pay more when booking in December. For low rates, September can be a great choice for travel to Puerto Rico. Flights to Puerto Rico from Kalispell in September are about $380 on average during September, but can be found for as low as $194.