Trekking in Bhutan is unlike anywhere else in the Himalayas. The walks are long and arduous but they are complimented by crystal air, lonely paths and views that defy description. The trails lead one through alpine meadows, rhododendron forests, around the foothills of the snow peaked Himalayas, emerald green valleys and  crystal lakes. One also gets the opportunity to see a wide variety of flora and fauna. One can travel for days without so much as seeing another person.
On all treks, one will be accompanied by a  guide, a cook, porters and luggage animals.  Trekkers need rarely to carry more than a day pack. Every precaution is taken to ensure the safety and comfort of the trekkers.
Most of the designated treks go above 9,000 ft (3,000 m) - 18,000 ft ( 6,000 m). Altitude sickness is an acute problem for trekkers in Bhutan and is not recommended for people who are not properly acclimatized or for those who suffer from high altitude sickness.
Trekking permits are required on all treks. The treks vary from short 3 day walks over relative low altitudes to over 3 week long treks which takes one through some of the highest passes in the kingdom.

Season
January-April, October-December
Climate (general) Days are normally warm. Nights can at times be very cool and in winter even below the freezing point. Monsoon showers in summer (heaviest July & August) and sometimes even in Spring and Autumn.
What to Bring Personal Clothing: Strong comfortable (clothing according to season). Preferably cotton even for summer. Wollen clothing for evenings and winter.
 For Trekking: Strong comfortable trekking boots, sun glasses, headgear, raincoat & warm clothing for the evenings.
 A sleeping Bag is a must. Medium to heavy is advised. A torch light will also be very handy.
Note For trekking a load of 25 kg is allowed..

IMPORTANT TIPS FOR TREKKERS

Climate

Days are normally warm. Nights can be quite chilly. In winter, the temperature is below freezing point. Monsoon shower in summer with heavy  rains in July and August.