April is the middle of spring in Bhutan. Temperatures are generally pleasantly warm in the day and cooler at night, but altitude has a huge effect on weather across the country. The southern parts of Bhutan bordering India are subtropical and can get very hot in April. The town of Gelephu, near the Royal Manas National Park, for instance, sees temperatures between 68 and 90° F (20 and 32° C) in April, and often gets even hotter.
Conditions in the mid-hills are more pleasant, with the conditions in Punakha (4250 feet/1300 m.) being warm to hot in April. Average temperatures range from 57 to 77° F (14 to 25° C). The capital Thimphu, which is higher at 7200 feet (2200 m.), sees cooler temperatures year-round, which in April range from 45 to 68° F (7 to 20° C).
Skies are generally clear in April, meaning you're likely to be treated to good mountain views, whether you're trekking or touring by car. However, later in April, and at higher altitudes, the humidity does increase and you may need rain gear just in case. There's the added attraction of beautiful blooming rhododendron flowers in April, which you can see while trekking or just walking in the hills.
Crowds & Costs
April is one of the busiest times for travelers to come to Bhutan, although traveler numbers are restricted by the high Bhutan visa costs, so nowhere in the country is every very crowded (with the exception of some festivals held at monasteries!).
If you're traveling to Bhutan in April you should expect to pay higher prices for tour packages. It's also a good idea to book flights as far in advance as possible, as there are limited connection points for flights into Bhutan (Delhi, Kathmandu, and Bangkok), so flights with convenient connections can book out quickly.
Where to Go
Almost all of Bhutan will be comfortable and accessible in April (hence why this is peak season!) Where you go should depend on what you're most interested in. If you're short on time and want to see the cultural highlights, then there's nothing wrong with sticking to the most popular circuit on Western Bhutan, which includes Thimphu, Paro, and the Punakha Valley/Wangdue, as well as the famous Tiger's Nest Monastery.
If you have a bit more time and a more generous budget, heading into central and eastern Bhutan is very worthwhile, and never more accessible than in April. The central Bumthang Valley (actually a collection of valleys) is considered the cultural and religious heartland of the nation. Eastern Bhutan is far less developed than the west and may require some small-plan flights to get to, but you're unlikely to see many or any other tourists there.
What to Do
April is a perfect time to trek in Bhutan. Most treks here require camping in tents, so the warmer temperatures of April (even though they'll still be cold at higher altitudes) are better suited to this activity. There are a range of great short and longer treks in Bhutan, so whether you're a highly experienced Himalayan trekker or a newbie, you should be able to find something to suit your needs and tastes.
Flower lovers should check out the Gazamchu Rhododendron Trek while the flowers are blooming in the spring. Experienced trekkers seeking a challenge could attempt the Jomolhari Trek or the Snowman Trek, often called the hardest trek in the world because of the number of nights spent at very high altitude.
Events in April
Paro Tsechu, late March or early April. One of Bhutan's many colorful Buddhist festivals with masked dances. This one is especially popular as it falls in peak tourist season, so book early if you want to see it.
Rhododendron Festival, mid-late April. The Lampheri Botanical Garden in Thimphu hosts a delightful rhododendron festival while the flowers are blooming, which is an ideal destination if you can't see them in the 'wild' while trekking.
Traveling to Bhutan in April? Check out these great itineraries
Bhutan Trekking Tour - 14 Days. April is a good time to go trekking in the Bhutanese Himalaya, and this itinerary combines cultural sightseeing with a seven-day Jomolhari Trek.
Snowman Trek: The Bhutanese Himalaya - 30 Days. Not one for the faint of heart but if you're a seasoned trekker, this is the ultimate high-altitude experience, passing through pristine mountain landscapes.
Dagala Thousand Lakes Trek - 12 Days. Enjoy views of Everest, Jomolhari, Masang Gang, and many other mountains on this six-day trek, combined with cultural sightseeing on this itinerary.