High season is late May through early September. Hotels are most likely to be full and charge their highest rates. Even then, though, weekends are cheaper and package plans reduce the bite, so advance planning has its rewards. The period from Christmas to New Year's is also busy (and more expensive), as are the days given to winter festivals in both Montréal and Québec City. Low season is during the least appealing months of March and April, when few events are scheduled and winter sports start to be iffy, and the late fall months of October and November, which have all but empty calendars.
Weather -- Temperatures are usually a few degrees lower in Québec City than in Montréal. Spring, short but sweet, arrives around the middle of May. Summer (mid-June through mid-Sept) tends to be humid in Montréal, Québec City, and other communities along the St. Lawrence River, and drier at the inland resorts of the Laurentides and the Cantons-de-l'Est. Intense, but usually brief, heat waves mark July and early August, but temperatures rarely remain oppressive in the evenings.
Autumn (Sept-Oct) is as short and changeable as spring, with warm days and cool or chilly nights. Canadian maples blaze with color for weeks.
Winter brings dependable snows for skiing in the Laurentides, the Cantons-de-l'Est, and Charlevoix. After a sleigh ride or a ski run in Parc Mont-Royal, Montréal's underground city is a climate-controlled blessing. February is the time for Québec City's robust Carnaval de Québec. Snow and slush are more or less constantly present from November to March.
