Ontario (Canada): where to swim in October?
Ontario, in October: the sea is at 5.7 °C on average along the coast, from 4.8 °C to 7.9 °C depending on the spot. Where the water is warmest (7.9 °C), it is very cold. Swimming takes training: very short dips, and a wetsuit to stay in longer.
Sea temperature, month by month
| Month | Average temperature | Depending on the spot | Where it is warmest |
|---|---|---|---|
| January | -1.4 °C | -1.6 °C – -1.2 °C | very cold |
| February | -1.5 °C | -1.6 °C – -1.3 °C | very cold |
| March | -1.5 °C | -1.6 °C – -1.3 °C | very cold |
| April | -1.4 °C | -1.5 °C – -1.2 °C | very cold |
| May | -1.1 °C | -1.3 °C – -0.7 °C | very cold |
| June | -0.7 °C | -1.2 °C – 0.6 °C | very cold |
| July | 1.8 °C | 0.5 °C – 4.0 °C | very cold |
| August | 8.3 °C | 7.4 °C – 9.2 °C | very cold |
| September | 8.3 °C | 7.0 °C – 10.6 °C | cold |
| October | 5.7 °C | 4.8 °C – 7.9 °C | very cold |
| November | 1.4 °C | 0.7 °C – 2.3 °C | very cold |
| December | -0.9 °C | -1.1 °C – -0.7 °C | very cold |
Compared with September, the water cools down by 2.6 °C in October. The warmest month: August (8.3 °C). The coldest: February (-1.5 °C).
Nearby, in October
- Quebec 6.0 °C · very cold
- New Brunswick 11.9 °C · cold
- Nova Scotia 13.9 °C · cool
- Nunavut -0.2 °C · very cold
- British Columbia 12.0 °C · cold
- Northwest Territories -0.7 °C · very cold
- Yukon 0.1 °C · very cold
And right now?
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). Ontario: water temperature
Frequently asked questions
What is the sea temperature in October?
Ontario, in October: 5.7 °C on average along the coast, from 4.8 °C in the coolest waters to 7.9 °C in the warmest (average of the years 2011 to 2025).
Can you swim in October?
Where the water is warmest (7.9 °C), it is very cold. Swimming takes training: very short dips, and a wetsuit to stay in longer.
What is the best month for swimming?
The water is warmest in August (8.3 °C on average) and coldest in February (-1.5 °C). Even where it is warmest, the water never reaches 20 °C in any month; the three warmest months are: September, August, October.
What temperature do you need to swim comfortably?
Below 15 °C the water is cold: the cold takes your breath away and tires you quickly. Between 20 °C and 25 °C most people find it pleasant. Below 10 °C it is very cold.
Where do these temperatures come from?
These are averages of the sea surface temperature from 2011 to 2025, computed from NOAA satellite images (OISST, one value about every 50 km), in a 100 km strip along the coasts of the main country: distant territories (overseas, remote islands) are not counted. It is an estimate, not a measurement taken at the beach: lakes and rivers are not included.