Planning for the weather is an important factor for making your trip to Alphonse Island a success, especially when you're splurging. The hottest months are usually April and May, with an average temperature of 28°C, while the coldest months are July and August, with an average of 26°C. The rainiest months in Alphonse Island are January, December, May and November, with each month seeing an average of 253 mm of rainfall.