AirHint found the following cheapest return flights from Houston (IAH) to Lisbon (LIS) in September 2025 (see full year).

Return flights

28 Sep - 07 Oct	Spirit Airlines
29 Sep - 08 Oct	Spirit Airlines
17 Sep - 24 Sep	Spirit Airlines
08 Sep - 29 Sep	Spirit Airlines
01 Sep - 11 Sep	Spirit Airlines
01 Sep - 22 Sep	Spirit Airlines
06 Sep - 13 Sep	Spirit Airlines
10 Sep - 21 Sep	Spirit Airlines
13 Sep - 01 Oct	Spirit Airlines
13 Sep - 20 Sep	Spirit Airlines
11 Sep - 21 Sep	Spirit Airlines

Also check the deals for one-way flights from Houston to Lisbon in September.

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 Houston to Lisbon in September from 480€

Return flights