Guatemala is one of the most colorful countries in Latin America. It offers excellent tours: its jungles with its incredible pyramids and Mayan constructions, magnificent volcanic landscapes, tropical landscapes full of wildlife, magnificent colonial cities and the impressive colors of each of its corners.
The best months to visit the country are from November to May and the worst are from June to October, as the rains will spoil most of your afternoons. The climate depends a lot on the altitude of the area you decide to visit. In the higher areas there is an "eternal spring": the days are warmer and the nights become quite cool. Meanwhile, the so-called lowlands (the jungle and the Caribbean area in general) are characterized by being too hot and sticky.
The minimum duration of your stay can be one week. During those 7 days, you will have time to visit places like Panajachel and Chichicastenango in good conditions. If you want to stay longer and visit the main cities, your stay can be extended up to 2 weeks. But be careful, since Guatemala is not a very safe country. There is a lot of crime in the area and crimes are often quite violent. One of the most dangerous areas is the central one. Try not to spend too much time in the middle and you can not do at night.
Communications are not very good. The roads that link town after town are pretty bad. The buses that make the tours are usually quite uncomfortable and unsafe. The best are the " Pullman " that operate on the main routes and cost a little more money.