AirHint found the following cheapest return flights from Milwaukee (MKE) to San Juan (SJU) in August 2025 (see full year).

Return flights

26 Aug - 30 Aug	Spirit Airlines
24 Aug - 30 Aug	Spirit Airlines
23 Aug - 30 Aug	Spirit Airlines
26 Aug - 31 Aug	Spirit Airlines
16 Aug - 19 Aug	United
28 Aug - 31 Aug	Spirit Airlines
24 Aug - 31 Aug	Spirit Airlines
18 Aug - 30 Aug	Spirit Airlines
18 Aug - 23 Aug	Spirit Airlines
23 Aug - 31 Aug	Spirit Airlines

Also check the deals for one-way flights from Milwaukee to San Juan in August.

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 Milwaukee to San Juan in August from 288€

Return flights