Weather can make or break a road trip, so here's some data about year-round temperatures in Iliomar to help you plan yours: The hottest months are usually November and October, with an average temperature of 26°C, while the coldest months are August and July, with an average of 24°C. The rainiest months in Iliomar are December, March, February and January, with each month seeing an average of 297 mm of rainfall.