Which months have the highest annual percentage of thunderstorms on Lake Ontario?

The months with the highest annual percentage of thunderstorms on Lake Ontario typically span from May to September. This period coincides with warmer weather as spring transitions into summer, leading to more unstable atmospheric conditions that can facilitate the development of thunderstorms.

During this timeframe, increased humidity and higher temperatures create the right conditions for thunderstorms to form, as rising warm air can lead to the development of cumulonimbus clouds, which are essential for thunderstorm activity. May is particularly notable as it often marks the beginning of the thunderstorm season, and this trend continues through to September, peaking in the summer months when convective storms are most common.

In contrast, the other options cover months that are either too early in the year, such as February to April or too late like August to October, when the frequency and intensity of thunderstorms generally decrease as temperatures begin to drop and air stability increases. Through understanding these seasonal patterns, one can appreciate why May to September is the prime period for thunderstorms on Lake Ontario.