In monsoon areas the two best seasons for trekking and climbing are the spring pre-monsoon (March, April & May) and the autumn post-monsoon (September, October and November). The pre-monsoon season is usually chosen for climbing as the weather is warmer, but for three weeks before the monsoon arrives the weather may be un-settled. This can sometimes be confused with the arrival of the monsoon itself.
The post-monsoon, autumn is he most popular time to trek, but if you are climbing on high mountains you will find the weather is colder and much windier than pre-monsoon. The post-monsoon is the best time for photography as the air is clear and the vegetation luxuriant in the lower regions.
By December temperatures begin to drop and snow can block the higher passes. During the winter trekking season the temperatures at altitude are tolerable when the sun is out. If it is windy and overcast, it can become cold very quickly, especially at night. The short span of day- light means you will also spend more time indoors or in your tent and you will need much heavier clothing. However, the trails are less crowded in winter, and if this is the only time you can get away it can still be a rewarding time to trek provides you are properly prepared. Some climbers are now deliberately choosing winter for the added challenge of cold, short days.
Because the monsoon has very little influence on the climate of Kashmir, the most suitable time to trek there is from May to October. This complements the gap in the trekking year in the eastern Himalaya.