If you’re looking forward to lots of outings with your partner, take a look at these details about year-round temperatures in Saipan: The hottest months are usually July and August, with an average temperature of 28°C, while the coldest months are February and March, with an average of 27°C. The rainiest months in Saipan are August, October, September and July, with each month seeing an average of 385 mm of rainfall.