If you’re planning to go hiking or trekking in Andorra, then the best time to visit the country is between April and October; the warmest months are between July and September, though, and this is also the time when the country’s villages are at their liveliest, with some interesting village festivals and cultural events happening. This is a pleasant time to visit, but remember that it’s also the peak of the summer tourist season, and you’ll need to get advance bookings in hotels if you’re to get accommodation.
If you’re going skiing in Andorra, as the bulk of the country’s tourists like to do, then aim at being in Andorra between December and March- that’s when the snowfall is heaviest, and the slopes are at their best. Some, but not all, ski resorts remain open even after the snowfall has stopped, by using manmade snow on the slopes.