Anytime is a great time to travel to Mexico! There's no bad time to visit Mexico, but certain times of the year may appeal to different people more than others, and some destinations are better at certain times of the year.
There are a few factors that you'll want to consider when planning the timing of your trip to Mexico: you'll want to have an idea of the weather, any festivals and events taking place at the time of your visit, and whether it is high or low season.
Although many people associate Mexico with hot weather, it's a big country with a wide range of climatic zones. The weather at sea-level tends to be warm to hot throughout the year, making for year-round beach weather (how convenient!) whereas at higher elevations the weather can get chilly to downright cold in the winter months, especially from November through January.
Mexico's beach resorts tend to be most pleasant between October and May (June to September can be very hot and humid) - and you should keep in mind that hurricane season lasts from June to November.
Read more about the weather in Mexico and see the annual high and low temperatures for different areas of Mexico: The Weather in Mexico.
Festivals and Events
If you'd like to experience one of the many fiestas that take place in Mexico, you should definitely time your trip to coincide with one. Some people dream of witnessing one of Mexico's unique celebrations like Day of the Dead, the Radish festival, or witnessing natural events like the annual Monarch buttefly migration, or releasing baby sea turtles on the beach. If you'd like to take part in one of those events, you'll want to plan the timing of your Mexican vacation accordingly. On the other hand, if your ideal Mexican vacation involves peace, quiet, and relaxation, you may want to plan your trip to avoid any of those other events. Of course, there are some places where you can find peace and quiet year-round - check out Mexico's Secret Beaches (perhaps not so secret anymore, but they'll definitely be less crowded than the more popular resort areas!).
High Season and Low Season
During school holidays at Christmas, Easter and during the summer months, Mexican families like to travel and you may find buses and hotels are crowded, so keep that in mind when planning your trip to Mexico. Beach destinations may be very crowded during Spring Break. For fewer crowds and good deals, you should travel at other times.
See also: Month-by-Month Guide to Mexico