Ontario: water temperature

At sea, 13.8 °C on average across 19 stations, from 9.2 °C (SLATE ISLAND) to 17.0 °C (PORT STANLEY). In fresh water, 12.1 °C on average across 15 stations, from 8.3 °C (Aubinadong River Above Sesabic Creek) to 17.0 °C (Port Stanley buoy).

See on the map

Sea and ocean

Lakes and rivers

Where to swim, month by month

The normal sea temperature each month along the coast: pick a month to see where the water is warmest and whether you can swim.

• January -1.4 °C · up to -1.2 °C
• February -1.5 °C · up to -1.3 °C
• March -1.5 °C · up to -1.3 °C
• April -1.4 °C · up to -1.2 °C
• May -1.1 °C · up to -0.7 °C
• June -0.7 °C · up to 0.6 °C
• July 1.8 °C · up to 4.0 °C
• August 8.3 °C · up to 9.2 °C
• September 8.3 °C · up to 10.6 °C
• October 5.7 °C · up to 7.9 °C
• November 1.4 °C · up to 2.3 °C
• December -0.9 °C · up to -0.7 °C

Warmest water today

Where these numbers come from

Every value is a real reading from an instrument, at its position: a buoy, a wharf, a river or lake station. It keeps the time it was measured. A reading too far from those of nearby stations is marked with a “?”. Between stations, the map gives a satellite or model estimate, always labelled as such.

Sources: Bouées d'Environnement Canada, Grands Lacs (Seagull), NOAA CO-OPS, NOAA NDBC, Relevés hydrologiques du Canada. Sources and credits

Nearby

• Quebec 18 stations · sea 9.8 °C · fresh water 10.6 °C
• Saskatchewan 10 stations · fresh water 3.7 °C
• New Brunswick 4 stations · sea 9.8 °C · fresh water 5.9 °C
• Nova Scotia 12 stations · sea 13.5 °C · fresh water 5.8 °C
• Nunavut 6 stations · fresh water 1.7 °C
• British Columbia 300 stations · sea 10.9 °C · fresh water 6.4 °C