Although Bhutan can still get some rain in September—especially earlier in the month—the worst of the monsoon has passed, and the weather becomes more comfortable for travel. If you'd like to completely avoid the rain, come to Bhutan in the last two weeks of September. While there are no guarantees it won't rain at all in late September, the likelihood of seeing significant rainfall is slim.
Temperatures are still warm in September, barely cooler than during the monsoon, but will likely feel more comfortable because of the reduced humidity. Altitude plays a huge part in temperatures in Bhutan. Most of the country is at quite a high altitude, but not all. The southern areas around the Royal Manas National Park are low, and remain hot in September, ranging from 75-88° F (24-31° C).
The mid-hills are a bit cooler, with Punakha (4250 feet/1300 m) having average temperatures of 68 to 81° F (20 to 27° C). The capital Thimphu, which is higher at 7200 feet (2200 m), sees cooler temperatures year-round, which in September range from 59 to 73° F (15 to 23° C).
Crowds & Costs
September is the start of Bhutan's peak autumn season. This season sees more visitors than the 'other' peak season, spring. But, because Bhutan restricts tourist numbers with its pricey visa and tour packages, the country is never incredibly busy with tourists.
If you're traveling to Bhutan in September specifically to see one of its fabulous festivals, book flights and tours as early in advance as possible, as good accommodation in areas where popular festivals are held can book out quickly.
Where to Go
With the exception of the southern areas around the Royal Manas National Park, which will still be pretty hot and steamy in September, everywhere in Bhutan should be accessible and enjoyable in September. If you want to go to more remote places (such as eastern or even central and far western Bhutan) that require long mountain drives or a domestic flight, it's still better to wait until later in September, to give the lingering monsoons a chance to pass.
What to Do
Later in September is a good time to go trekking, as road access to trailheads should be clear again after the monsoon, and skies become clear. There are many great trekking routes to choose from, depending on your experience, fitness, and preferences. The Snowman Trek is a classic, and a bucket-list trek for many experienced trekkers. It's considered one of the hardest treks in the world, as you need to cross nine very high passes. It takes around 25 days.
A shorter (but still challenging) trek that takes around two weeks is the Jomolhari-Laya Gasa Trek. Sometimes called the most scenic in Bhutan, the route takes trekkers past alpine meadows, across high mountain passes, and through lush jungles. If you want something shorter and less challenging, there are plenty of walking options around villages and towns, too.
Events in September
Thimphu Tsechu, four days in September or October. This is one of the most important tsechus in Bhutan, and is very popular with visitors, so book your tour and flights early to see this one.
Haa Tsechu, held over two days in the small western Bhutan town. It's divided between Haa Dzong and the Lhakhang Karpo chapel.
Tamshing Phala Choepa, Bumthang Valley. There are several days of festivities in the central Bhutanese Bumthang Valley in September, at Tamshing Gompa and Thangbi Gompa.
Traveling to Bhutan in September? Check out these great itineraries
Jumolhari Round Trek and Cultural Tour - 17 Days. This itinerary includes a challenging trek and cultural attractions, for travelers who want the best of both worlds in Bhutan.
Bike Tour of Bhutan - 15 Days. Get an inside look at the fascinating culture and beautiful scenery of Bhutan on this two-week cycling adventure around the Bhutanese countryside.
Western Bhutan and Phobjikha - 7 Days. Longing for an adventure that's truly off the beaten track? This immersive, culturally rich tour of western Bhutan is just the thing.