Portugal is a popular year round destination but like with any tourist area, there are high seasons and low seasons. The high seasons tend to be when people will flock to the area, and the low seasons are where the weather might not be as good and as such, tourism tends to slow down. The low season can be a very good time to visit Portugal and the Algarve in particular, so you can enjoy the sights without all of the other tourists.
Portugal is milder than the UK all year, but if you want the warmest weather possible, this will inevitably mean travelling during high season. This is a good time to go if you don’t mind the cost, you want the best of the weather, and you want to make the most of the touristy activities that are on offer. However, for many tourists, the quieter low season is a very charming time to visit the Algarve.