When to go — Ontario

Ontario is ideally visited from June to September for summer or in January-February for frozen falls and winter atmosphere. Summer (June-September) offers optimal conditions: 22-28 °C temperatures in Toronto, long days (sunset at 9pm in June), all sites open (Maid of the Mist mid-April to November), festivals galore (Toronto Caribbean Carnival in August, TIFF in September, Toronto Pride in June). It's also high tourist season at Niagara Falls — book 2-3 months ahead for July-August.

Indian summer (mid-September to mid-October) is exceptional in southern Ontario — blazing maple and oak foliage in Algonquin Park (peak late September), Niagara-on-the-Lake (mid-October, autumn-coloured vineyards), Gatineau Park near Ottawa. Climate still pleasant (15-22 °C by day), reduced crowds after Labour Day (1st Monday of September), hotel rates down 20-30% from July-August.

Winter (December-March) offers a radically different experience. Partially frozen Niagara Falls in January-February during cold snaps (striking spectacle of turquoise-blue ice), year-round illuminations and Winter Festival of Lights (November-February, 3 million lights). Toronto under snow (free skating at Nathan Phillips Square), Winterlude in Ottawa (winter festival, first fortnight of February, world's longest skating rink on the Rideau Canal). Toronto hotel rates down 30-40%. But harsh cold: -8/-1 °C Toronto, possible spells at -20 °C with violent Lake Ontario winds, risky winter driving.

Shoulder season (April-May, November) is less favourable: April-May bring unstable weather (temperatures 5 to 20 °C, frequent rains), November the first snows. Prefer summer, Indian summer or winter for an optimal trip.