Mexico's climate is extremely varied, primarily due to its diverse terrain. Because it is such a large country, the weather can (and will) change from one destination to another.
North of the Tropic of Cancer, weather conditions in Mexico are milder than those in the south, where conditions are tropically warm and humid throughout most of the year.
Generally the coastal areas are warm (often hot) with high humidity; the central plateau is more moderate, while in the higher elevations cooler temperatures are the norm.
The Pacific coastal areas (June - September) receive more rainfall than the inland regions; the Yucatan is rainy throughout the year, but rain showers are brief and sunshine is common.
Hurricanes occasionally strike the eastern coastline from June through October.
(in general terms)
Spring: April - June
Summer: July - September
Fall: October - December
Winter: January - March