The hottest month in Ontario is August when the average maximum temperature is 21°, average temperature is 18° and average minimum temperature is 16°.
The coolest month in Ontario is January when the average maximum temperature is -5°, average temperature is -9° and average minimum temperature is -13°.
The longest days in Ontario are in June, with an average of 15.7 hours of daylight per day. December has the shortest days with an average of 8.7 hours of daylight per day.
The sunniest days in Ontario are in July which has the most hours of sunshine per day with an average of 9.9 hours of sunshine per day, making it a sunny month with few clouds. December has the least sunshine with an average of 2 hours of sunshine per day, making it not a particularly sunny month.
The ultraviolet index is the highest in July when it reaches 8.8 and lowest in December when it reaches 1.1.
An ultraviolet index reading of 8 to 10 indicates a very high risk of harm from unprotected sun exposure. Unprotected skin risks burning in less than 15 minutes. Take extra precautions because unprotected skin and eyes will be damaged and can burn quickly. Tanning will be safest before 10am and after 4pm but only with a good application of sun screen. For those with sensitive skin stay in the shade and wear protective clothing, a wide-brimmed hat, and UV-blocking sunglasses. Generously apply broad spectrum SPF 30+ sunscreen every 2 hours, even on cloudy days. Watch out for relections from water that may increase ultraviolet exposure.
The warmest sea water temperatures in Ontario are found in August when they peak at 24° and lowest in February when they dip to 4°.
The sea is best for swimming between June and December when the temperature is above 14° which is cold for swimming, a full wet suit is required to spend any length of time in the sea.
The wettest month in Ontario is March with 3.4cm of rain and December has the most days of rain with 4.9 days with some rain, a very dry time to visit the beach.
The driest month in Ontario is April with 1cm of rain and the least days of rain with 2.8 days with some rain, a very dry time to visit the beach.
The most humid month in Ontario is August with a dew point (an indicator of humidity) of 16° which is OK for most but slightly uncomfortable for some.
The least humid month in Ontario is January with a dew point of -8° which is a bit dry for some.
The most windy month in Ontario is December when the average maximum windspeed is 34kmh and the average wind speed is 22kmh.
The least windy month in Ontario is June when the average maximum windspeed is 22kmh and the average wind speed is 13kmh.