Weather will likely play an important role when you plan your trip to Ono Island, and keep in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually February and March with an average temp of 81°F, while the coldest months are August and July with an average of 75°F. The rainiest months in Ono Island are March, February, January, and April, with each month seeing an average of 12 inches of rainfall.