The weather and climate in Nepal play a large part in affecting when visitors come to Nepal and it is useful to understand the seasonal variations so that visitors can choose to visit at the optimum time for the activates they wish to do.
The Nepali weathers Seasons
The weather in Nepal is reasonably stable and the climate naturally forms 4 main seasons.
Winter (December, January, February)
The Nepali Winter sees predominately high pressure bringing clear skies and dry weather. The temperatures are warm in the day but as the sun sets the temperature falls quickly and nights are often very cold.
During the Pre monsoon you can expect more variable weather but with predominantly clear mornings and overcast afternoons. Both the days and nights will be warm and the temperature will gradually increase as the season progresses. Thunderstorms are quite common at this time of year and are sometimes combined with short bursts of heavy rain or hailstones.
Monsoon (Mid-June, July, August, Mid-September)
The Monsoon season dominates Nepali climate and is a period of low pressure which brings frequent rain showers and storms. The majority of the rain falls in the afternoon and night-time but there are also occasional days of continuous rain. During this season the temperature and humidity is very high during both the night and day.
Post-Monsoon (Mid-September, October, November)
The Post Monsoon Season brings a return to stable high pressure giving mainly clear skies, sunshine, warm days and cool nights.
The Best Season to Visit Nepal
Each of Nepal’s climatic seasons offer something different and visitors do come to Nepal all the year round. However, the weather that suits most people is during the Pre and Post Monsoon seasons. It is at this time that the majority of visitors come to Nepal.
These two main tourist seasons (Pre-Monsoon, March, April, May, Mid June and the post-Monsoon, Mid-September, October, November). Both tend to be fairly dry, and to provide pleasant conditions for trekking, rafting and sightseeing. During the Pre-monsoon visitors will have the benefit of flowering plants, but visibility is sometimes reduced with hazy conditions. Post-monsoon normally provides good visibility.
For trekking below 4000m, the day time temperatures in these seasons will normally allow visitors to be comfortable in a t-shirt and light sweater. Above 4000m a fleece jacket may also be needed. At altitudes above 3000-3500m, night time temperatures will be low (often down to around freezing), but a down jacket or staying tucked up comfortably in a warm tent or lodge will be enough to stay comfortable.
Trekking is still possible outside the main seasons and during the monsoon months (mid-June, July, August, mid-September) the rain-shadow areas of the upper Marsyandi and Kali Gandaki valleys, and Dolpo receive far less rain than the Khumbu or Annapurna areas. During the winter conditions can also be good although much colder, but be aware that on occasions in January, February and March the higher passes and valleys are sometimes unreachable owing to snow fall.
Rafting is possible throughout the year in Nepal. Seasonal variations in temperature and rainfall affect the water levels in the rivers and determine which rivers are best run at any one time. Optimum seasons for running each river will be advertised by good operators on their websites. Nepalguideinfo.com for listed companies.