The best time to visit Niagara Falls is June through August, when warm temperatures (22–28°C), long daylight hours, and the full roster of attractions — including Maid of the Mist and Cave of the Winds — are all in operation. Summer is peak season, so expect crowds on the Canadian promenade and higher hotel prices, especially on weekends.
Late April and May offer a sweet spot: temperatures are pleasant (12–20°C), cherry blossoms and tulips bloom in Queen Victoria Park, visitor numbers are lower, and most major attractions have reopened after their winter hiatus.
September and October bring autumn foliage that turns the gorge a blaze of red and orange — arguably the most beautiful backdrop the falls can offer — with noticeably fewer tourists and more reasonable rates.
November to March is off-season. Cave of the Winds and Maid of the Mist close, but the falls themselves freeze partially, creating spectacular ice formations that attract photographers. The Festival of Lights (mid-November to January) draws visitors to the illuminated park. Temperatures regularly drop below -10°C, so pack accordingly.
Avoid major US and Canadian holiday weekends (Canada Day July 1, US Independence Day July 4, Labour Day) if crowds concern you — these days see the longest waits at popular attractions.