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 Gran: The hottest months are usually July and June, with an average temperature of 14°C, while the coldest months are January and February, with an average of -5°C. The snowiest months in Gran are January, December, February and October, with each month seeing an average of 43 cm of snowfall.