Ontario (Canada): where to swim in May?
Ontario, in May: the sea is at -1.1 °C on average along the coast, from -1.3 °C to -0.7 °C depending on the spot. Where the water is warmest (-0.7 °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 April, the water hardly changes in May. The warmest month: August (8.3 °C). The coldest: February (-1.5 °C).
Nearby, in May
- Quebec 1.1 °C · very cold
- New Brunswick 6.5 °C · very cold
- Nova Scotia 6.0 °C · very cold
- Nunavut -1.4 °C · very cold
- British Columbia 10.1 °C · cold
- Northwest Territories -1.4 °C · very cold
- Yukon -1.0 °C · very cold
And right now?
For the temperature measured right now, station by station and to the hour: Ontario: water temperature
Frequently asked questions
What is the sea temperature in May?
Ontario, in May: -1.1 °C on average along the coast, from -1.3 °C in the coolest waters to -0.7 °C in the warmest (average of the years 2011 to 2025).
Can you swim in May?
Where the water is warmest (-0.7 °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.