Lake Ontario Water Temperature

(Today) Aug 2025

21.8°C / 71.2°F

The water will feel tepid. Swimming will be tolerable without a wetsuit, although it will take a little getting used to. If you intend to stay in the water for a while a 3/2mm wetsuit will be ideal.

Current weather

19°C / 67°F
(clear sky)
Partly cloudy
Wind
21 mph
Humidity
61%

Water temps is based on average surface temperatures measured throughout Lake Ontario.

Map showing Lake Ontario locations. Click on pins to view water temperature.

16 locations listed in Lake Ontario.