temperature helena mt
Home : Climate Graphs: Montana : Helena. Average Temperatures for Helena. Helena's coldest month is January when the average temperature overnight is 9.9Â°F. In July, the warmest month, the average day time temperature rises to 83.4Â°F. The driest month in Helena is February with 0.38 inches of precipitation, and with 1.82 inches June is the wettest month.