Visiting local bars in Gillette is better when you know what the weather holds. These rainfall averages and temperatures can help you decide the best time for bar-hopping. The hottest months are usually July and August, with an average temperature of 21°C, while the coldest months are February and January, with an average of -3°C. The snowiest months in Gillette are April, January, February and March, with each month seeing an average of 14 cm of snowfall.