If you're hoping to get lost in the rain on your romantic getaway, take a look at these details about year-round temperatures in Hartington: The hottest months are usually July and August, with an average temperature of 22°C, while the coldest months are January and February, with an average of -3°C. The snowiest months in Hartington are January, December, October and March, with each month seeing an average of 20 cm of snowfall.