Water Temperature

Water temperature is an influential factor that affects if, when, where and how people swim, including whether or not they may prefer a wet suit.

Cold Water Swimming Considerations

Swim Season

The Ontario swim season starts in mid May and continues until late September.  During this time water temperatures can range from 10°C / 50°F to 24°C / 75°F.  Great lake temperatures tend to be somewhat lower.

Acclimation

For newcomers a reasonable target to aim for is to be comfortable at a water temperature of 15°C / 60°F.  This may mean starting training over short periods at colder temperatures than this outdoors, then you will become more acclimatized to the cold water.  When training outdoors, always have a swim buoy and safety boat or swim partner(s).

Swim Speed

Among other open water swimming factors, water temperature can impact swim speed.  Swimmers may not be able to swim as fast in cold outdoor water as they do in warm pool water as a result of energy expenditure being inversely proportional to the temperature of the water to cover a given distance in a given time.  Because of this and other open water swimming factors, the duration of an outdoor swim will typically be greater than pool swim times.  As a result of these slow down factors, it is essential to train for a distance greater than that which you are going to attempt to swim.

Weather Conditions

Water temperature can be heavily influenced by local weather conditions, cold up-swells and/or a local stream entering the lake.

Data Sources

• Smart Buoys - A couple of beaches (currently Cherry Beach and Kew-Balmy Beach) have smart buoys that collect real-time water temperature at all times, as long as they are functioning properly.  This site is regularly updated from these smart buoy's data feeds.  The hope is to add more smart buoys at other popular beaches in the Greater Toronto Area (GTA) in 2023.
• Smart Watches - Open water swimmers in the GTA can now share water temperature data collected while swimming with an equipped Garmin smart watch, such as a fenix and Forerunner 945.  Water temperature data is automatically posted after swims, once the watch connects to a paired smartphone that uploads it to the user's Garmin Connect account, which in-turn shares the data with this site.  When multiple swimmers share water temperatures in the same area, the median of each swim within 24 hours of the latest swim is used.  Sign up and connect your Garmin watch to share the water temperature with others where you swim!
• Swim Drink Fish - Works at the confluence of water, people, and storytelling, using community science, technology, and communications to connect people to water.  Through a network of Community Water Monitoring Hubs, Swim Drink Fish measures and shares water temperatures at a number of beaches and sites in the GTA, among many other water quality measurements they also monitor.  Results are posted as soon as they are entered online, and this site will be regularly updated from those results.

Want to improve water temperature data on this site?  Become a community scientist!