Saint Lawrence River — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in the Saint Lawrence River, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in the Saint Lawrence River today is 2.8°C.
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 |
|---|---|---|---|
| APR 11 | 2.7°C | 8.5°C | |
| APR 12 | 2.8°C | 8.5°C | |
| APR 13 | 2.6°C | 8.5°C | |
| APR 14 | 2.7°C | 8.5°C | |
| APR 15 | 2.7°C | 8.5°C | |
| APR 16 | 2.9°C | 8.5°C | |
| APR 17 | 2.9°C | 8.5°C | |
| APR 18 | 2.8°C | 8.5°C | |
| APR 19 | 8.5°C | 3.1°C | |
| APR 20 | 8.5°C | 3.4°C | |
| APR 21 | 8.5°C | 3.7°C | |
| APR 22 | 8.5°C | 3.9°C | |
| APR 23 | 8.5°C | 4.2°C | |
| APR 24 | 8.5°C | 4.5°C | |
| APR 25 | 8.5°C | 4.8°C |
* 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 | 2°C | 6°C | 9°C |
| February | 2°C | 6°C | 9°C |
| March | 1°C | 6°C | 11°C |
| April | 1°C | 9°C | 16°C |
| May | 6°C | 14°C | 21°C |
| June | 11°C | 17°C | 22°C |
| July | 17°C | 20°C | 24°C |
| August | 17°C | 21°C | 24°C |
| September | 11°C | 16°C | 20°C |
| October | 8°C | 13°C | 16°C |
| November | 3°C | 8°C | 16°C |
| December | 3°C | 5°C | 8°C |
Saint Lawrence River: Water Temperature by Location
Saint Lawrence River: Weather Forecast
April 19
April 20
April 21
April 22
Location & Local Information
Source Lake Ontario
• location Kingston, Ontario / Cape Vincent, New York
Mouth Gulf of St. Lawrence / Atlantic Ocean
• location Quebec, Canada
Length 500 km (310 mi)
The Saint Lawrence River, stretching between the United States and Canada, is known for its clear, cold waters that vary greatly in temperature depending on the season. In the summer months, water temperatures typically range from 60°F to 70°F (15°C to 21°C), which can be inviting for swimmers in areas where conditions are safe. However, even during the warmest months, the water remains on the cooler side compared to other rivers, offering a refreshing experience for those seeking relief from the summer heat.
Swimming in the Saint Lawrence River is most popular in designated areas, such as near parks, beaches, and calmer stretches of the river. The Thousand Islands region, in particular, is a favored spot for water activities, offering stunning scenery and generally manageable conditions. However, swimmers should be aware of the river’s strong currents in certain areas, as well as colder temperatures in deeper sections or near the river’s flow into the Atlantic Ocean. Overall, the Saint Lawrence River provides a unique and scenic environment for swimming, best enjoyed in the summer and with proper attention to safety.