Cheapest return flights from Ontario to Denver in December from $58

AirHint found the following cheapest return flights from Ontario (ONT) to Denver (DEN) in December 2025 (see full year).

Return flights

24 Dec - 31 Dec Frontier Airlines direct
24 Dec - 29 Dec Frontier Airlines direct
11 Dec - 14 Dec Frontier Airlines direct
12 Dec - 14 Dec Frontier Airlines direct
24 Dec - 16 Jan Frontier Airlines direct
05 Dec - 12 Dec Frontier Airlines direct
31 Dec - 07 Jan Frontier Airlines direct
15 Dec - 20 Dec Frontier Airlines direct
15 Dec - 21 Dec Frontier Airlines direct
14 Dec - 19 Dec Frontier Airlines direct
19 Dec - 21 Dec Frontier Airlines direct
03 Dec - 08 Dec Frontier Airlines
21 Dec - 02 Jan Frontier Airlines direct
29 Dec - 03 Jan Frontier Airlines direct
31 Dec - 03 Jan Frontier Airlines direct
23 Dec - 03 Jan Frontier Airlines direct
29 Dec - 01 Jan Frontier Airlines direct
24 Dec - 10 Jan Southwest Airlines direct
22 Dec - 02 Jan Frontier Airlines direct
22 Dec - 03 Jan Frontier Airlines direct

Also check the deals for one-way flights from Ontario to Denver in December.

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