Planning for the weather is an important factor for making your trip to Manzanillo a success, especially when you're splurging. The hottest months are usually September and May with an average temp of 79°F, while the coldest months are January and February with an average of 75°F. The rainiest months in Manzanillo are July, November, October, and May, with each month seeing an average of 17 inches of rainfall.