The best time to visit Nepal for rafting is from March to Early June and September to early December. Here is why:

Mid-October to November
The best time to visit Nepal and go for any expedition, trekking, hiking is in the month of October and November, the fall season. With clearer skies, sunny days, makes Nepal ideal for those who want to trek and go on an adventure sports like rafting. You will get to experience with exciting river runs.

Rafting in the Month of March to early May
March happens to be early summer in Nepal and has a long hot days with lower water flow. That means, you won’t get to see a fast flow of river in this month which is the best of those who are trying out rafting for the first time. As the season changes, in the month of May, due to some snow melt and pre-monsoon storms, rivers gradually raise increasing the flow of river.
In both of the months, you will not get the thrilling experience while rafting. However, is best for those who wants to take a taste of this sport.

Rafting: June to August
Due to monsoon rains, the rivers in Nepal carry ten times their lower water flow that can flood in very high speed. This makes most of the river in Nepal insanely difficult. Only some rivers in Nepal commercially run during the Monsoon season: Trisuli, Upper Seti, and Upper Sun Kosi.
Month: May to June and September to Early October
The month of May to June and September to Early October is the post monsoon season in Nepal. Due to the monsoon run-off, rivers in Nepal flows in extremely high pressure and volume. In the time of extremely high flow of river, it’s very dangerous to be in the river. In order to attempt rafting in this season, you and your team should be very experienced and should have knowledge of the rivers and need to have a very experienced rafting company.

Month December
In December, due to start of winter season, the days are short. The water in the rivers have a good flow however are too cold to enjoy. If you still want to experience rafting in this season, it’s better to wear wet-suits or consider shorter trips like hiking, site seeing or roaming around the city area.

The rivers are vastly categorized into different classes according to the difficulty in maneuvering the raft on the river. The categories of river are:

Class 1: These are the simplest river with little to know obstacles in the way and have a very gentle flow. This is the place to begin with if you’re just getting into the sport of rafting.

Class 2: These Rivers have relatively stronger flow than the class 1 rivers but still are not uncontrollable; they have a little amount of obstacles too.

Class 3: These Rivers are similar to class 2 rivers and have relatively more flow than class 1 rivers and also have a lot more obstacles a good understanding about rafting should be enough for you to get along these rivers.

Class 4: These Rivers usually have a long distance between the beginning and the end. These Rivers contains a lot of obstacles and also has a lot of strong waves, a good ordination is required between the teammates to complete these classes of rivers.

Class 5: rivers from class 5 have relatively long route and along the route is a strong flowing river with a lot of obstacles like large rocks, and boulders. Avoiding and rafting through those obstacles takes a lot of energy, thus only a team with experience should raft of these kinds of rivers.

Class 6: These Rivers are strong flowing and have a lot of obstacles like huge rocks and holes that may make it impossible for the raft to go pass through. Thus these types of rivers are impossible to raft on.