Alliston (ON) Temperature by Month

Alliston, Ontario, Canada has an average annual maximum temperature of 13°C (55°F), ranging from -1°C (30°F) in January to 27°C (81°F) in July. Below you'll find a full monthly breakdown and a comparison with cities worldwide.

The climate in Alliston is dynamic, ranging widely from very cold in winter to comfortable in summer. Nights are significantly colder, with lows dropping from 15°C (59°F) in July to -11°C (12°F) in January.

The chart below illustrates the average maximum day and minimum night temperatures in Alliston by month:

The minimum temperature is often recorded between 4 AM and 6 AM, while the highest temperature is usually reached at 3 PM, when the sun's heating effect is strongest. July, the warmest month, gets 295 hours of sunshine.

The chart below shows the average temperature throughout the year:

Alliston's average annual maximum temperature is 13°C (55°F). To put that in context, here's how it compares to a few well-known destinations:

Lisbon, Portugal averages 21°C (70°F) annually, warm summers, mild winters, and rain mainly in the cooler months.

Queenstown, New Zealand averages 10°C (50°F) annually, remember seasons are flipped, so its coldest months fall in June and July.

Boston, USA averages 16°C (61°F) annually, with four distinct seasons and cold winters that rival northern Europe.

Adelaide, Australia averages 21°C (70°F) a year, with warm summers, mild winters, and relatively low rainfall year-round.

Temperature alone doesn't tell the whole story, humidity plays a big role in how warm or cold it actually feels. High humidity in summer makes the heat feel more intense, particularly once temperatures climb above 25°C. In winter, the same humidity can make cold air feel sharper than the thermometer suggests.

In the cooler months, when temperatures drop below 10°C, high humidity makes the cold feel more cutting than it would in dry conditions.

In Alliston, January is the coolest month, with average highs of -1°C (30°F) and humidity around 72%, considered high. In July, the warmest month, temperatures average 27°C (81°F) with 53% humidity, conditions that feel moderate. For a full picture, see our humidity page.

Climate temperature data is typically calculated as a 30-year average. This smooths out year-to-year variability and gives a more reliable picture of what a place is actually like, rather than what happened in any single unusual year.

The readings come from a range of sources, land-based weather stations, ocean buoys, ships, and satellites. That data is collected by weather services around the world, then pooled, quality-checked, and averaged to produce the climate records you see here.

Seasonal temperature shifts influence more than just how warm it feels, they also drive changes in rainfall, cloud cover, and wind patterns throughout the year.

Warmer air holds more moisture, which tends to mean heavier or more frequent rain during the warmer months. When temperatures drop in winter, any precipitation that does fall is more likely to come as snow or sleet, though in Alliston this rarely lasts long on the ground.

For more on Alliston's weather, including monthly rainfall, sunshine hours, and humidity, visit our Alliston climate page.