Weather will likely play an important role when you plan your trip to Windsor, but bear in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually July and August, with an average temperature of 21°C, while the coldest months are January and February, with an average of 0°C. The snowiest months in Windsor are January, February, March and April, with each month seeing an average of 15 cm of snowfall.