Weather will likely play an important role when you plan your trip to Monterrey, and keep in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually February and January with an average temp of 78°F, while the coldest months are July and June with an average of 73°F. The rainiest months in Monterrey are June, May, July, and April, with each month seeing an average of 11 inches of rainfall.