Farming is not without its risk, however, in the form of wind erosion, drought, thunderstorms and hailstorms and unseasonably early autumn frosts. The chinook sweeps down from the Rocky Mountains and has been known to raise temperatures as much as 16 o C in a single day. The Great Lakes-St. More than half the Canadian population lives close to the Great Lakes or along the St. Lawrence River. Here, winter brings heavy snowfalls.
Summers tend to be longer and more humid than elsewhere in Canada.
Rainfall varies little year to year and is ample enough to sustain some of the best farming areas in Canada. Warm, sunny days and crisp, cool nights make the fall season popular. The combined influence of continental air masses with air currents off the ocean give this region one of the most rugged and most variable climates anywhere in the country. In winter, mean temperatures can vary markedly as Arctic air is replaced by maritime air from passing storms. Snowfall is relatively heavy, and fog is common in spring and early summer.