Lake Ontario water temperature

Lake Ontario, Grimsby · Lake

The current water temperature at Lake Ontario is 21.7 °C (as of September 1, 2026, source: NOAA NDBC).

Lakes stratify in summer: bathing-warm on top, markedly colder a few metres down. Measurements are taken at the surface — right where you swim.

21.7 °C

Measured: September 1, 2026 · continuously updated

💧 Water 21.7° · ☀️ Air 23.0° · high today 27.0°

Temperature trend of recent weeks

Lake Ontario — Photo: Gogerr · CC BY-SA 4.0 · Wikimedia Commons

Measurement series & statistics

This measurement series includes 1219 data points since July 4, 2026.

Lowest recorded value: 16.8 °C on August 3, 2026 · highest value: 25.3 °C on August 17, 2026.

Nearby waters

Lake Erie, Port Colborne · 42.1 km away22.5 °C Atlantic, Buffalo, NY · 65.8 km away22.7 °C Lake Erie, Buffalo · 65.8 km away22.7 °C Lake Erie, Buffalo · 66.9 km away23.0 °C Eighteenmile Creek at Burt, New York · 69.6 km away21.0 °C

More measuring points: Lake Ontario

Sodus Point Nearshore Monitoring23.0 °C Oswego, NY (274)22.4 °C Cape Vincent22.3 °C Oswego22.2 °C Prince Edward Pt21.7 °C Sodus Point, NY21.3 °C

Frequently asked questions

Can you swim at Lake Ontario right now?
The current water temperature is 21.7 °C. See live swimming conditions, weather and quality in the BrrChecker app.

How warm is the water at Lake Ontario?
Currently 21.7 °C (updated continuously).

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