If you're looking forward to lots of outings with your partner, take a look at these details about year-round temperatures in Guapiles: The hottest months are usually April and March, with an average temperature of 19°C, while the coldest months are January and February, with an average of 18°C. The rainiest months in Guapiles are October, June, August and September, with each month seeing an average of 599 mm of rainfall.