Planning for the weather is a good way to make your trip to Palmerston Island relaxing and enjoyable, especially when you're splurging. The hottest months are usually March and February, with an average temperature of 27°C, while the coldest months are August and September, with an average of 25°C. The rainiest months in Palmerston Island are January, February, December and March, with each month seeing an average of 263 mm of rainfall.