Weather will likely play an important role when you plan your trip to Lewistown, 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 17°C, while the coldest months are February and December, with an average of -4°C. The snowiest months in Lewistown are April, February, October and March, with each month seeing an average of 30 cm of snowfall.