Lake Ontario Water Temperature

(Today) Dec 2025

4.9°C / 40.8°F

The water will feel very cold. For the hardcore only! The water is now dangerously cold and most people will risk hypothermia if not equipped with a thick, 6/5mm wetsuit along with boots and a hood

Current weather

-2°C / 29°F
(broken clouds)
Partly cloudy
Wind
37 mph
Humidity
59%

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.