Good morning Claire,
Thanks for getting in touch, I have pasted an excerpt below of information that will be contained in your final information documents, I hope this helps,
Kindest,
Ben
------------------------------
Climate & Clothing
Summer thunderstorms are common all over Canada. Occasionally, these may become severe. Tornados also occur throughout Canada, with May to September being prime months. The peak season is June and early July in southern Ontario, Alberta, southeastern Québec, and a band stretching from southern Saskatchewan and Manitoba, through to Thunder Bay. The interior of British Columbia and western New Brunswick are also tornado zones. Earth tremors occur in the western mountains. Forest fires can occur at any time, regardless of the season, particularly in the grasslands and forests of western Canada.
Note: These general guidelines apply mainly to the settled areas of southern Canada. Travellers heading to northern areas, such as the Yukon, the Northwest Territories, Nunavut and Labrador, should bring warm clothing for all but the summer months (and even in summer, at least a lightweight jacket is advisable). See the individual provinces and territories sections for more details.
March: Moderate temperatures. Winter clothing with some medium weight clothing.
April: Milder days but the evenings are cool. Medium weight clothing including a topcoat and umbrella is recommended.
May: Warm days but cool at night. Medium weight and summer clothing recommended.
June: Warm, summer clothing with some medium weight clothing for cool evenings. The weather in June is ideal for travel and all outdoor activities.
July/August: These are the warmest months of the year. Lightweight summer clothing is recommended.
September: Warm days and cool evenings. Light- to medium weight clothing recommended.
October: Cool, with the first frost in the air.
November: Cool to frosty. Medium- to heavyweight clothing is recommended. First signs of snow.
December/January/February: Winter temperatures. Winter clothing is necessary (eg overcoat, hat, boots and gloves). Heavy snowfall in most provinces.
In the winter months it is useful to take sunglasses with you as the reflection of the snow can be a strain on the eyes. Rubber soled shoes are also recommended.