Eastern Ontario - Climate

Climate

The climate of Eastern Ontario is humid continental with large seasonal variation. Snow and ice are dominant during the winter season. Ottawa receives close to 250 cm (100 in) of snowfall over an average winter and snow usually remains on the ground for a couple of months, at minimum.

Winters are long and celebrated in Eastern Ontario. The average temperature in January is -6°C (21 °F). In recent years, there seems to be a trend towards snow free periods, even in mid-winter. However, in the winter months of 2008, there were records levels of snow fall.

Ice storms are also relatively common, especially on lower terrain if compared with other parts of the country. One such large storm caused vast power outages and affected the local economy, known as the 1998 Ice Storm. Winters are more severe and longer along the Ottawa River, particularly in higher terrain of Renfrew County than further south along the Upper St. Lawrence River shoreline.

Summers are fairly warm and humid in the Ottawa and St. Lawrence valleys, usually lasting a little longer than winter does in duration. The average July maximum temperature is 27 °C (80 °F). Temperatures occasionally exceed 35 °C (95 °F), and during periods of hot weather, high humidity is often an aggravating factor, pushing the temperature into the 40's (100's) with the humidex. Thunderstorms are on occasion severe, causing tree and property damage.

Spring and fall are changeable seasons, prone to extremes in temperature and unpredictable swings in conditions. Average annual precipitation is around 950 mm (37 in.).