If you're looking forward to lots of outings with your partner, take a look at these details about year-round temperatures in Cajamarca: The hottest months are usually August and September, with an average temperature of 12°C, while the coldest months are July and August, with an average of 12°C. The rainiest months in Cajamarca are March, February, December and January, with each month seeing an average of 249 mm of rainfall.