Planning for the weather is an important factor for making your trip to Lihir Island a success, especially when you're splurging. The hottest months are usually May and October with an average temp of 81°F, while the coldest months are August and September with an average of 80°F. The rainiest months in Lihir Island are March, December, April, and January, with each month seeing an average of 16 inches of rainfall.