There are three distinct regions in Mexico. East Coast, Central, and West Coast. This is certainly over simplified, but for a visitor it provides enough distinction to judge climate. East Coast is predominately the Yucatan Region and the primary tourist zones are from just north of the City of Cancun, south through the City of Playa Del Carmen, then south along the Caribbean.
The Sea Coast, This area is always humid, with temperatures ranging from 68 to 86 degrees, January to March; 71 to 89 degrees April to June; 75 to 91 Degrees July to September, and 68 to 87 degrees October through December. Beaches here have a predominate on shore breeze.
The Central region, is the oldest in Mexico. The climate here varies as does the terrain. Expect very dry arid air south of Mexico City, with desert like conditions. This area leads to a higher mountain range to the south, where temperatures are more moderate, with frequent showers. North of Mexico City is typical of weather conditions found in Texas and New Mexico, in the United States.
The West Coast, returns to humid air, with seasonal temperatures that mimic the East Coast region. On Shore winds, similar to the Santa Anna winds of California, frequent this area. The proximity to California allows this region to enjoy a vivid tourism business, and tourist areas are found between older, large cities all along the coast. Recent improvements in security in some of the main tourist areas has allowed this region to awaken again after a security scare for a few years.
However, prior to your trip carefully select and use appropriate caution in selecting which areas to visit.