AirHint found the following cheapest return flights from Denver (DEN) to San Juan (SJU) in October 2025 (see full year).

Return flights

05 Oct - 10 Oct	Frontier Airlines
02 Oct - 05 Oct	Frontier Airlines
28 Oct - 04 Nov	Southwest Airlines
22 Oct - 26 Oct	Southwest Airlines
28 Oct - 11 Nov	United
25 Oct - 08 Nov	United
09 Oct - 14 Oct	Southwest Airlines
29 Oct - 12 Nov	United
30 Oct - 13 Nov	United	direct
27 Oct - 10 Nov	United
17 Oct - 20 Oct	United	direct
02 Oct - 05 Oct	United	direct
17 Oct - 31 Oct	United	direct
31 Oct - 14 Nov	United
06 Oct - 13 Oct	Delta
18 Oct - 01 Nov	United
09 Oct - 14 Oct	United	direct
19 Oct - 02 Nov	United
05 Oct - 10 Oct	United	direct

Also check the deals for one-way flights from Denver to San Juan in October.

The deals are updated regularly. The prices may go up as tickets are purchased by other travellers. Only the cheapest flights are offered. Select a price to book and secure these cheap prices.

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Cheapest return flights from Denver to San Juan in October from 228€

Return flights