Lake Ontario Water Temperature

(Today) Jul 2025

20.7°C / 69.2°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

23°C / 74°F
(scattered clouds)
Partly cloudy
Wind
8 mph
Humidity
85%

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.