Climate Insights for Ontario

The climate in Ontario is temperate. The average annual temperature is 14°C and approximately 276mm of precipitation falls per year. December is the wettest month, receiving around 44mm of rainfall. Ontario is in the Northern Hemisphere. Summer begins at the end of June and lasts through September. The summer months are: July, August, June. The coldest months are January, December, February, when temperatures can drop to -3°C. Light snow can occur between January and December.

Ontario has a wide annual temperature range, spanning 40°C from the coldest to warmest months. July is the hottest month, with daytime highs reaching 37°C and an average of 29°C. The coldest month is January, when overnight lows fall to -3°C and the daily average is 0°C. On average, daily temperatures fluctuate by about 13°C between overnight lows and afternoon highs. The sharpest temperature change occurs between September and October, with a 8°C shift in average temperatures.

Ontario is a quite dry location, receiving approximately 276mm of precipitation annually, which averages out to around 23mm per month. The wettest month is December, averaging 44mm of rainfall. January and February also tend to see above-average precipitation. The driest month is July, with just 2mm. That's 43mm less than December, the wettest month. Rainfall is heavily concentrated in certain months, creating a distinct wet and dry season. Visitors should plan around these patterns, as the difference between peak and low months is dramatic. Light snowfall can occur between January and December, totalling around 43cm annually. January is the snowiest month with approximately 14cm.

Ontario is relatively calm, with an average annual wind speed of 8km/h. For context, sustained winds below 12km/h are generally light, while anything above 25km/h is considered strong. The windiest month is May, averaging 10km/h, though still comfortable for most outdoor activities. The calmest conditions occur in December, with average winds dropping to 6km/h, making it an ideal period for wind-sensitive activities. There is moderate seasonal variation in wind speed, with a 4km/h gap between the calmest and windiest months.

It is currently summer in Ontario, which began on June 21, 2026. Ontario is in the Northern Hemisphere, where spring begins in March, summer in June, autumn in September, and winter in December. The warmest period peaks in July at around 37°C, while the coldest stretch bottoms out in January near -3°C. Autumn is next, beginning on September 23, 2026 (8 days from now).

The best time to visit Ontario is during May, June and September, when the weather is most comfortable for travellers. During these months, average temperatures hover around 21°C with modest rainfall averaging 15mm per month. By contrast, July can be uncomfortably hot with highs reaching 37°C, while January is the coldest period with lows dropping to -3°C. With minimal rainfall expected, you can pack light and plan outdoor activities with confidence.

The table below shows monthly climate averages for Ontario based on historical weather data. Min and max temperatures represent typical overnight lows and afternoon highs for each month, shown in degrees Celsius (°C). Precipitation is measured in millimetres (mm) and indicates the average total rainfall per month. Snow is measured in centimetres (cm) and reflects average monthly snowfall accumulation. Wind speed is the average sustained speed in kilometres per hour (km/h). All values are based on averages from over 10 years of historical weather data. The current month is highlighted for quick reference.