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Lake Ontario

Lake Ontario Current Water Temperature and Forecast

On this page, you will find comprehensive information about the water temperature in Lake Ontario, including current readings, historical data and trends, monthly averages, as well as weather forecasts and upcoming temperature predictions. We find every spot where you can swim and tell you what the water temperature is there today and throughout the year.

Current Lake Water Temperature Information

6.8°C

TODAY

7.3°C

YESTERDAY

5.7°C

A WEEK AGO

As of today, the minimum water temperature in the Lake Ontario 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.

Analysis, Historical Data, and Forecast of Water Temperature

Water Temperature Chart for Lake Ontario Over the Last 30 Days

Today the water temperature in Lake Ontario is higher than the same day in previous years. The water temperature range here in April is from 0°C to 12°C. The water temperature is trending upward, and it has increased both over the past 30 days and the past week.

The forecasted water temperature values for Lake Ontario are presented in the table below.

The actual water temperature values near the shore may differ by a few degrees from the stated values. For the development of the forecast, we use our own mathematical model that takes into account the current water temperature changes, historical data, and key weather trends, including wind strength and direction, and air temperature in each specific region.

Daily Water Temperature Chart

Date	Current	Average	Forecast
Apr 12	5.7°C	6.0°C
Apr 13	5.8°C	6.0°C
Apr 14	5.5°C	6.0°C
Apr 15	5.6°C	6.0°C
Apr 16	6.7°C	6.0°C
Apr 17	7.1°C	6.0°C
Apr 18	7.3°C	6.0°C
Apr 19	6.8°C	6.0°C
Apr 20		6.0°C	6.8°C
Apr 21		6.0°C	6.8°C
Apr 22		6.0°C	6.8°C
Apr 23		6.0°C	6.8°C
Apr 24		6.0°C	6.8°C
Apr 25		6.0°C	6.8°C
Apr 26		6.0°C	6.8°C
Apr 27		6.0°C	6.8°C

* Current - Actual water temperature value

** Average - Average water temperature on this day in recent years

*** Forecast - Our water temperature forecast

Water Temperature Ranges in Lake Ontario by Month

January

Minimum	Average	Maximum
0°C	3.5°C	7°C

February

Minimum	Average	Maximum
-1°C	1°C	3°C

March

Minimum	Average	Maximum
-1°C	2.5°C	6°C

April

Minimum	Average	Maximum
0°C	6°C	12°C

May

Minimum	Average	Maximum
8°C	11°C	14°C

June

Minimum	Average	Maximum
14°C	18°C	22°C

July

Minimum	Average	Maximum
16°C	21°C	26°C

August

Minimum	Average	Maximum
20°C	22.5°C	25°C

September

Minimum	Average	Maximum
16°C	19.5°C	23°C

October

Minimum	Average	Maximum
10°C	15°C	20°C

November

Minimum	Average	Maximum
5°C	9.5°C	14°C

December

Minimum	Average	Maximum
0°C	4.5°C	9°C

Monthly Water Temperature Histogram for Lake Ontario

Water Temperature in Cities and Towns on Lake Ontario

Toronto

Canada (Ontario)

6.5°C

Kingston

Canada (Ontario)

3.0°C

Oakville

Canada (Ontario)

5.7°C

Mississauga

Canada (Ontario)

6.5°C

Hamilton

Canada (Ontario)

5.8°C

Rochester

United States (New York)

4.9°C

Greater Napanee

Canada (Ontario)

3.9°C

St. Catharines

Canada (Ontario)

7.3°C

Lake Ontario Weather

APRIL 20

2°C / 6°C

light drizzle

rain: 17% | wind: 34 km/h

APRIL 21

3°C / 7°C

moderate rain

rain: 46% | wind: 44 km/h

APRIL 22

4°C / 8°C

slight rain

rain: 46% | wind: 51 km/h

APRIL 23

3°C / 6°C

overcast

rain: 11% | wind: 25 km/h

Water Temperature in Lake Ontario: General Trends and Swimming Opportunities

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.

Geographical Location of Lake Ontario

Nearby Lakes

Frequently Asked Questions About Lake Ontario and its Water Temperatures

What is the current water temperature in Lake Ontario?

The water temperature today in Lake Ontario ranges from 37°F (3.0°C) to 45°F (7.3°C).

What is the water temperature in Lake Ontario during the summer months?

The average water temperature in Lake Ontario during the summer months is typically between 64°F to 73°F (18°C to 23°C), and it can reach up to 79°F (26°C) at its warmest. However, in some years, the temperature may exceed this range.

What is the water temperature in Lake Ontario in May?

The average water temperature in Lake Ontario in May ranges from 46°F to 57°F (8°C to 14°C).

What is the water temperature in Lake Ontario in September?

The average water temperature in Lake Ontario in September is typically between 61°F to 73°F (16°C to 23°C).

Where is Lake Ontario located?

Lake Ontario is located in North America, forming part of the border between Canada and the United States, with Ontario to the north and New York to the south.

Is it possible to swim in Lake Ontario and what are the possibilities for this?

Yes, it is possible to swim in Lake Ontario, with various public beaches and parks along its shoreline providing swimming areas during the warmer months.

What are the coordinates of Lake Ontario?

Lake Ontario is located at coordinates 43.6230°N 77.7270°W.

What species of fish can be found in Lake Ontario?

Lake Ontario is home to species such as lake trout, rainbow trout, smallmouth bass, northern pike, and yellow perch.