Lake Ontario, NW Lake Ontario Ajax · Lake
The current water temperature at Lake Ontario is 18.4 °C (as of July 17, 2026, source: NOAA NDBC).
Can you swim at Lake Ontario right now?
The current water temperature is 18.4 °C. See live swimming conditions, weather and quality in the BrrChecker app.
How warm is the water at Lake Ontario?
Currently 18.4 °C (updated continuously).
How warm is at Lake Ontario in July?
In July, the water temperature recently averaged 20.0 °C.