Lake Ontario — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in Lake Ontario, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in Lake Ontario today is 39°F.
Water Temperature: Daily Trends, Historical Records, and Forecast
❌ As of today, the minimum water temperature ranges less than 41°F (5°C). Such water is extremely cold and not recommended for swimming without proper preparation. In these conditions, the risk of hypothermia is very high, and prolonged exposure to the water can be hazardous to your health. If you decide to swim, it is important to have the appropriate gear, such as a wetsuit. Typically, only experienced swimmers or those who practice winter swimming venture into such waters. It is important to note that these swimming tips and recommendations apply only in good weather. When the air temperature is below 68°F (20°C), and sometimes even below 77°F (25°C), swimming can be unpleasant even with relatively high water temperatures.
Water Temperature Chart Over the Last 30 Days
Table of Daily Sea Temperature Data
| Date | Current | Average | Forecast |
|---|---|---|---|
| MAR 9 | 36°F | 37°F | |
| MAR 10 | 41°F | 37°F | |
| MAR 11 | 41°F | 37°F | |
| MAR 12 | 44°F | 37°F | |
| MAR 13 | 44°F | 37°F | |
| MAR 14 | 42°F | 37°F | |
| MAR 15 | 40°F | 37°F | |
| MAR 16 | 39°F | 37°F | |
| MAR 17 | 37°F | 39°F | |
| MAR 18 | 37°F | 39°F | |
| MAR 19 | 37°F | 39°F | |
| MAR 20 | 37°F | 39°F | |
| MAR 21 | 37°F | 38°F | |
| MAR 22 | 37°F | 38°F | |
| MAR 23 | 37°F | 38°F |
* Current - Actual water temperature value
** Average - Average water temperature on this day in recent years
*** Forecast - Our water temperature forecast
Actual nearshore water temperatures may fluctuate by several degrees from the reported values, especially following heavy rainfall or extended periods of strong winds. Certain wind patterns can cause colder, deeper waters to rise and replace the sun-warmed surface water, leading to noticeable variations.
Our forecast is based on a proprietary mathematical model that considers real-time water temperature changes, historical trends, key weather patterns, wind strength and direction, and air temperature specific to each region. Additionally, we incorporate data from other resorts to enhance accuracy.
Monthly Water Temperature Range (Min, Max & Average)
| Month | Min | Avg | Max |
|---|---|---|---|
| January | 32°F | 38°F | 45°F |
| February | 30°F | 34°F | 37°F |
| March | 30°F | 37°F | 45°F |
| April | 32°F | 43°F | 54°F |
| May | 46°F | 54°F | 61°F |
| June | 57°F | 64°F | 72°F |
| July | 61°F | 70°F | 79°F |
| August | 66°F | 72°F | 77°F |
| September | 61°F | 67°F | 73°F |
| October | 50°F | 59°F | 68°F |
| November | 41°F | 49°F | 57°F |
| December | 34°F | 42°F | 48°F |
Lake Ontario: Water Temperature by Location
Lake Ontario: Weather Forecast
March 17
March 18
March 19
March 20
March 21
Location & Local Information
Max. length 193 mi (311 km)
Max. width 53 mi (85 km)
Surface area 7,323 sq mi (18,970 km2)
Average depth 283 ft (86 m)
Max. depth 802 ft (244 m)
Lake Ontario, the smallest by surface area but one of the deepest of the Great Lakes, offers a mix of natural beauty and urban waterfronts. Stretching between the United States and Canada, it provides numerous opportunities for swimming, boating, and relaxing along its scenic shores. With both sandy beaches and rocky coves, the lake caters to a variety of recreational preferences.
The water temperature in Lake Ontario is influenced by its depth and the surrounding climate. During the summer months, surface temperatures near the shore typically range from 68°F to 75°F (20°C to 24°C), with July and August being the warmest and most comfortable for swimming. However, deeper areas of the lake remain significantly cooler year-round, and spring waters can feel brisk, often in the 50s°F (10°C to 15°C). The lake’s cooler nature makes it a refreshing escape during hot summer days, especially in shallow, sun-warmed bays.
Swimming is popular at well-maintained beaches like Ontario Beach Park in Rochester and Sandbanks Provincial Park in Canada. These locations often have designated swimming areas with lifeguards and facilities to enhance safety and convenience. While Lake Ontario offers excellent conditions for swimming, occasional advisories related to water quality, particularly after heavy rainfall, mean it’s important to check local updates before heading in. The combination of scenic surroundings and accessible recreation makes Lake Ontario a cherished destination for water enthusiasts.