Weather: Spring and autumn seasons are no doubt the best time to visit Nepal. Other seasons like summer, monsoon, and winter are equally good depending on the purpose. For tours and treks in the Himalayas that are in rain shadow - Mustang, Inner Dolpo, Kailas and Tibet - summer (May, June, July) and end of Monsoon (September) season are better. Weather in winter is pleasant in the lower mountain area and in southern part of Nepal where Lumbini (Buddhist pilgrimage site) and National Parks are located. Winter is also nice to do short treks in the lower foothills and meet people when they are generally free for festivals and leisure.
Autumn Monsoon. The rain normally ends middle of September. Sometimes rain continues into the first week of October. Generally the weather in October and November is cold at night and warm during the day. Skies remain clear throughout most of the day. It is a good time for views of the snow peaks. From the second half of November the weather starts getting colder and in the mountains snow starts to fall. The average temperature above 3000 to 4000m is around 4 to 18 degree Celsius. Above 4000 meter, the night temperature falls below zero to minus 10 degree Celsius. Below 3000meter, average temperature ranges around 10 to 25 degree Celsius. In the Tarai region the nights are cold and days hot.
The winter starts December and remains until February. Usually at Christmas and New Year fresh snow falls on the mountain above 3000 meter. The Temperature drops to 2 degree Celsius at night in the middle hills and less than zero degree in the mountain above 2500m. During the day it is sunny and warm with an average temperature of 19degree Celsius.
Spring is great with a cool breeze, but the sun is shining. The mountain landscape is covered with snow and you can see the colourful flowers of rhododendron forests inn March and April. You can see birds migrating and wild life. There is less snow on the mountain passes. Usually the sky is clear in morning and evening but during the day it is cloudy. In April the weather becomes warmer (25 to 30 degree Celsius) and in May the temperature reaches around 35 degree Celsius.
Summer starts from the middle of May and remains until beginning of July. This is the hottest period.
The Monsoon rain start from beginning of July. Heavy rainfall occurs at the end of July (375 to 800mm). It becomes lesser (375 to 400mm) at the end of August and the beginning of September. Usually, by the middle of September the weather becomes drier. The rain does not fall every day, not even in the middle of monsoon. There are several dry days in between. The temperature is pleasant (20 degree Celsius) in the middle Mahabarat range and cooler in the mountain above 3000 meter.
The average temperatures and rainfall during peak summer and winter in three most popular tourist areas: