Weather will likely play an important role when you plan your trip to Tulagi Island, and keep in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually May and November with an average temp of 80°F, while the coldest months are August and July with an average of 80°F. The rainiest months in Tulagi Island are March, December, January, and February, with each month seeing an average of 17 inches of rainfall.