Weather is probably a major factor when you plan your trip to Mornington Island, but bear in mind that cheaper options are usually available when the weather isn’t as good. The hottest months are usually November and October, with an average temperature of 30°C, while the coldest months are June and July, with an average of 24°C. The rainiest months in Mornington Island are January, February, March and December, with each month seeing an average of 204 inches of rainfall.