Planning for the weather is an important factor for making your trip to Alter do Chão a success, especially when you're splurging. The hottest months are usually September and October, with an average temperature of 29°C, while the coldest months are January and February, with an average of 26°C. The rainiest months in Alter do Chão are March, April, February and May, with each month seeing an average of 511 mm of rainfall.