If you’re looking forward to lots of outings with your partner, take a look at these details about year-round temperatures in Gerenzano: The hottest months are usually July and August, with an average temperature of 22°C, while the coldest months are January and December, with an average of 5°C. The rainiest months in Gerenzano are November, October, May and August, with each month seeing an average of 194 mm of rainfall.