BEST TIME FOR TREKKING: When and how you go trekking depends greatly on the time of year. Generally speaking, the best months to trek are October-November (post-monsoon) and April-May (pre-monsoon). It is possible to trek throughout the year but trekkers must be aware that bad/ freak weather can strike in any season. Below are details of trekking conditions throughout the year:
Autumn is normally dry, stable and very clear. Temperatures are usually moderate during this period making it a good time for any trek. It can be cold at night higher up, but not as cold as the winter months (December-January). At low elevations it may still be hot during the day. Autumn is the most popular time for trekking so don’t expect solitude on the more popular routes.
Winter is usually dry and settled but it is a lot colder. Snow can fall in regions as low as 2500m, sometimes lower. It may be difficult to reach some of the higher passes (4000m+) due to snow & ice. The high-altitude treks require good gear and experience in cold-weather conditions as temperatures at 5000m can drop below -20°C and heavy snow can fall. Below 2000m temperatures can be pleasant though valleys are often fog- or haze-filled.
The cool and clear blue skies in Spring makes it the best time to visit Nepal. The days are warm with good sunshine and the evenings are cooler, sometimes reaching freezing point at night. The flowers are in full bloom and the Rhododendron flowers colour the hillsides red. Spring is also known to be the best time to Climb the high mountain peaks such as Mt. Everest.
PRE-MONSOON: May-mid June
It gets that much hotter, hazier and unsettled in May & early June. The warming Asian landmass has begun drawing up air from the south, ushering in the pre-monsoon a season of erratic weather and increasingly frequent afternoon storms. If you are looking for solitude on your trek, this is a good time to go. It is also a good time for going high but be prepared for rain, especially in the traditionally wet areas of Annapurna and eastern Nepal.