Bhutan is open all seasons. For example, for a good view of the mountains the dry season is ideal, from November to April (although rainfall can still be fairly high in some months). In general, the Bhutan climate varies considerably with elevation. A subtropical climate prevails in the southern Great Plains with warm, humid summers and mild winters around 15°C. The east-central hills and valleys are drier and more temperate than in the west. In the western valleys, temperatures are more severe and snow occasionally occurs in winter. In the north of the country, there's a rather difficult alpine climate, especially towards the highest peaks, constantly under snow. It should be noted that the north constitutes the territory of the Great Himalayas and other peaks rising to more than 22,965ft. They are only inhabited by the Bjop (pastoralists and nomadic herders), accustomed to this type of extreme conditions. In other words, you only get there after intense training!
Main areas to visit: Western Valley (e.g. capital Thimphu, Paro, Punakha), Southern Bhutan (e.g. Gelephu, Phuentsholing), eastern valleys (e.g. Sakteng Park)
January: heading south
Just like the western valley, the localities of this area are quite cold in January with 5°C on average but plenty of sunshine. The eastern valleys are not much warmer with an average temperature of 4 to 6°C. The southern zone is, on the other hand, much more summery with an average temperature of 24°C. In this area, you are strongly advised to take the road between Phuentsholing and Thimphu, moving from tropical vegetation to conifers in a single journey, all wrapped in a blanket of mist, giving the place an almost mystical feel.
February: a few degrees higher in the valleys
It gets a few degrees warmer in the western and eastern valleys (7°C on average) with the sun still present. Well wrapped-up, you can stroll through the streets of the capital, including Norzim Lam, for souvenirs in shops selling fabrics, books, mystical masks and other objects of all kinds. In the south, the weather is always more summery with 27°C and beautiful bright days. Note: celebrate Losar, the Tibetan new year, in February. The Bhutanese paint their house and host numerous archery and dart tournaments.
March: slightly heavier rainfall
Rain is fairly moderate but can fall on certain days. The southern zone begins to warm considerably with an average temperature of 31°C. The valleys, in turn, are around 8-10 °C (10 to the east and 8 to the west), heralding the start of the warm season.
April: humidity increases.
As usual, the eastern valleys warm up a little before their western neighbours, with an average temperature of 14°C. On the other hand, the rains intensify, particularly in the west with about twenty days of rainfall. As the humidity increases, visibility on the peaks is slightly worse than in the previous month. The south is also fairly humid but has summer temperatures with an average temperature of 31°C. With about 18 rainy days a month, it is possible to check the weather forecast before planning a trip. It should be noted that trekking is recommended during this period because the mountains are covered with rhododendrons in bloom. But you'll need rainwear. It is worth noting that this is when the Tsechu festival in Paro is celebrated. In the itinerary: ritual dances and a huge thangka (religious image) parade.
May: rainy season approaching
The valleys are close to spring temperatures with an average temperature of 13°C to 15°C. However, as the wet season approaches, rainfall increases throughout the territory, particularly in the south, which is subject to a subtropical climate. In general, the days fluctuate between precipitation and lightening. Therefore, a raincoat is an essential for this visit.
June: the monsoon turns up
Wherever you are in Bhutan in June, you'll get rained on. Especially as monsoon clouds can sometimes cause cancellations at Paro Airport and roads are sometimes flooded. The only consolation is that wild flowers cover the high valleys during this time of year.
July: Bhutan is waterlogged
In the middle of the monsoon, July is very rainy and cloudy. The south is especially hot and humid, which makes this time of year quiet with tourists. Be aware that in July the country experiences the highest rainfall rate in the entire Himalayas. We'd recommend that you start your journey at the end of September to avoid the rainy season.
August: slightly drier with a drop in rainfall
Rainfall declines just slightly in August, but is still high enough to disrupt your visit as it can rain heavily almost every day. On the flip side, it means that the vegetation is very lush at this time of year and mushrooms, mangoes and avocados grow everywhere.
September: opt for the end of the month
The first half of September is still rather rainy, while the last few weeks enjoy a beautiful blue sky and several big festivals take place as the weather improves. In the capital, Tsechu is celebrated with four days of intense dance spreading joy to the whole country. The Haa region in the west and the Bumthang valley in the north also celebrate.
October: the tourist season is back in full swing
The month of October is the best time to visit Bhutan, as the climate is milder and the mountains are clearly visible. So this is a great month for climbing the peaks. On the downside, the country is full of tourists and especially trekkers, so book your trip well in advance. Also make sure to wear warm clothes if you plan to climb, as the nights are cold in the high mountains. The western valley cools somewhat to 12°C, but the eastern zone, on the other hand, still retains spring temperatures at 18°C on average. And you can expect about 30°C to the south.
November: Bhutan cools down
The western valleys cool to 10°C on average, so pack accordingly. The eastern region is, as usual, slightly warmer, fluctuating between 11°C and 16°C during the day. Conversely, the southern zone becomes very pleasant, at around 28°C. If you are in Mongar, in the central part of the country, you should know that the tsechu annual festival is held there at this time. The festival is on a smaller scale to others in the country and attracts less tourists.
December: winter has arrived
As winter sets in, it is sometimes accompanied by snowfall at high altitudes and passes in the eastern and western areas can sometimes be blocked as a result. Make sure you wrap up well in the eastern and western valleys, while in the south you'll enjoy the mild and pleasant weather.