AirHint found the following cheapest one-way flights from Ontario (ONT) to San Juan (SJU) in August 2025 (see full year).

One-Way flights

11 Aug	United
18 Aug	Southwest Airlines
19 Aug	Southwest Airlines
22 Aug	Southwest Airlines
23 Aug	Southwest Airlines
08 Aug	Southwest Airlines
13 Aug	Southwest Airlines
21 Aug	Southwest Airlines
09 Aug	Southwest Airlines
27 Aug	Southwest Airlines

Also check the deals for return flights from Ontario 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.

Book a cheap hotel in San Juan

Cheap car rent in San Juan

Cheapest one-way flights from Ontario to San Juan in August from 144€

One-Way flights