If you’re looking forward to lots of outings with your partner, take a look at these details about year-round temperatures in Jundiai: The hottest months are usually September and December, with an average temperature of 22°C, while the coldest months are July and June, with an average of 18°C. The rainiest months in Jundiai are January, December, February and November, with each month seeing an average of 210 mm of rainfall.