This data the coastal Sunnyside Beach water temperature today, tomorrow and the upcoming days. Besides, you can also get information about the weather and surf forecast, as well as the data on sunrise / sunset and moonrise / moonset at a given point on any given day.
Water temperature in Sunnyside Beach today is 19.3°C. Based on our historical data over a period of ten years, the warmest water in this day in the Lake Ontario near Sunnyside Beach was recorded in 2018 and was 22°C, and the coldest was recorded in 2013 at 15.9°C. Water temperature in Sunnyside Beach is expected to drop to 17.5°C in the next 10 days. September average water temperature in Sunnyside Beach is 19.5°C, the minimum temperature is 14.6°C, and the maximum is 23.1°C.
The swimming season in Sunnyside Beach lasts from July to September. During those months, Sunnyside Beach water temperature does not drop below 20°C and therefore suitable for comfortable swimming. The average water temperature in Sunnyside Beach in winter reaches 3.7°C, in spring 4.6°C, in summer the average temperature rises to 18.3°C, and in autumn it is 13.8°C.
21 September 2025 |
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today temp |
19.3°C |
20 September 2025 |
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yesterday temp |
19.3°C |
Another important indicators for a comfortable holiday on the beach are the presence and height of the waves, as well as the speed and direction of the wind. Please find below data on the swell size for Sunnyside Beach. We calculate the swell size based on the mean wave height (trough to crest) of each third highest wave. For more information on surf forecasts for the next ten days, please visit sea state forecast Sunnyside Beach. Data in table shown for 21 September 2025, time in GMT 0 format (you can change the time zone on the sea state forecast page)
0-3 h | 3-6 h | 6-9 h | 9-12 h |
---|---|---|---|
2' 5" | 2' 6" | 2' 7" | 2' 3" |
0.74 m | 0.76 m | 0.78 m | 0.69 m |
12-15 h | 15-18 h | 18-21 h | 21-24 h |
---|---|---|---|
1' 9" | 1' 4" | 1' 4" | 1' 7" |
0.53 m | 0.4 m | 0.41 m | 0.48 m |
Data in a table show Sunnyside Beach temperature today (21 September 2025). For more information and forecast for a few days, go to the weather forecast Sunnyside Beach.
0-3 h | 3-6 h | 6-9 h | 9-12 h |
---|---|---|---|
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16.5°C | 16.4°C | 16.3°C | 17.4°C |
12-15 h | 15-18 h | 18-21 h | 21-24 h |
---|---|---|---|
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19.5°C | 21°C | 20.5°C | 19.8°C |
You may also be interested in other sections of our site for Sunnyside Beach: Sunrise and Sunset, Tides
These figures shows the average, minimum and maximum monthly water temperature in Sunnyside Beach. In addition to the table values, the graph below displays of changes average surface temperature during the year. Values are calculated based on the data over the past 10 years. Using them, you can check the water temperature in Sunnyside Beach on any day of this period that interests you. Click on the month link and you will see a table for each day, or alternatively you can view the temperature curve of the month and select 2 different years you want to compare, either in a table or as a curve
Month | Avr | Min | Max | |
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January | 3.4°C | 1.5°C | 5.2°C | cold |
Water temperature in Sunnyside Beach in January | ||||
February | 2.6°C | -0.4°C | 4.5°C | cold |
Water temperature in Sunnyside Beach in February | ||||
March | 2.7°C | -0.1°C | 5.8°C | cold |
Water temperature in Sunnyside Beach in March | ||||
April | 3.8°C | 0.3°C | 6.5°C | cold |
Water temperature in Sunnyside Beach in April | ||||
May | 7.4°C | 2.9°C | 16.7°C | cold |
Water temperature in Sunnyside Beach in May | ||||
June | 13.9°C | 5.3°C | 21°C | cold |
Water temperature in Sunnyside Beach in June | ||||
July | 19.9°C | 12.7°C | 24.9°C | cold |
Water temperature in Sunnyside Beach in July | ||||
August | 21.1°C | 13.9°C | 24.8°C | warm |
Water temperature in Sunnyside Beach in August | ||||
September | 19.5°C | 14.6°C | 23.1°C | cold |
Water temperature in Sunnyside Beach in September | ||||
October | 14.1°C | 6.1°C | 19.9°C | cold |
Water temperature in Sunnyside Beach in October | ||||
November | 7.9°C | 4.3°C | 13.6°C | cold |
Water temperature in Sunnyside Beach in November | ||||
December | 5°C | 2.2°C | 7.6°C | cold |
Water temperature in Sunnyside Beach in December |