Planning for the weather is an important factor for making your trip to Nuevo Vallarta a success, especially when you’re splurging. The hottest months are usually May and June with an average temp of 79°F, while the coldest months are February and January with an average of 71°F. The rainiest months in Nuevo Vallarta are August, September, July, and June, with each month seeing an average of 10 inches of rainfall.