Nepal sees enormous climatic variation between the plains of the Terai, the mid-hills where Kathmandu and Pokhara are located, and the high Himalaya. Weather in the hill cities is very hot in May, often above 90°F in the daytime, and even higher on the Terai. Although Nepal's monsoon starts in June, late May will likely see the start of rain and thunderstorms throughout the country. High altitude temps can still get cold at night, but most places in the Himalaya will be warm and sunny in the day.
Crowds & Costs
May is the tail end of Nepal's spring tourism season. The popular trekking trails remain busy, and teahouse accommodation can fill up fast. Hotels tend to charge a peak-season fee in May. By the end of May, with the monsoon approaching, visitor numbers start to decline.
May is prime trekking season in Nepal, with warm temperatures making both teahouse and camping treks comfortable. Visibility isn't always so clear in May, however, as humidity and dust build before the monsoon arrives in June. You may experience some rain and brief thunderstorms on treks in May, which actually has the benefit of clearing the air and making mountain views better.
For more on trekking in Nepal, check out this article.
Where to Go
Almost all trekking trails throughout the country are accessible and comfortable in May. Those at lower altitudes, such as around the Kathmandu Valley and Pokhara, may be uncomfortably hot for some trekkers, so this is an ideal time to head to the mountains. Camping treks are also good at this time of year.
Unfortunately, the heat and dust build to unpleasant levels in Kathmandu in May, with winds making conditions all the more uncomfortable. Head out to the hills, mountains, and rivers instead, where you'll enjoy much cleaner air.
What to Do
If you're up for a real challenge, the Everest season runs through May. Otherwise, less difficult (and equally rewarding) climbs are also accessible. Mera Peak is one example—it's the highest trekking peak in Nepal, with an ascent to 21,246 feet and great camping in wild and remote valleys along the way. See Everest Base Camp in May for more about trekking in the Everest Region this month.
May is also a good month to head out on some of the Himalaya's more remote trails in the Far West or Far East, as camping is more comfortable at this time of year.
With warm weather and water, May is an ideal time to go on a white-water rafting or kayaking trip, ranging from 1-12 days. Water levels prior to the monsoon can be low, however, so some rivers are better than others for a May trip. Here's some more information about whitewater rafting in Nepal.
Mountain biking trails are still dry and make for an enjoyable adventure activity in May. Read more about great mountain biking options in this article.
Traditional Nepali festivals (whether Hindu or Buddhist) usually follow a lunar calendar. This means that some festivals that fall in May one year may be in April or June the next. One festival that often falls in May is the Rato Machchendranath festival in Patan. During this Newari festival, a god statue is pulled through the streets in an enormous chariot for several days.
Traveling to Nepal in May? Check out these great itineraries.
Western Nepal Homestay Trek with Bardia Safari. Humla is a remote region of Western Nepal, and May is one of the months when it's accessible. This trek takes you through the area's river valleys and high peaks, with homestays along the way. After your trek, visit Bardia National Park for a native wildlife safari.
Kanchenjunga Trekking. One of Nepal’s most rewarding treks, Mt. Kanchenjunga lies on the eastern border of Nepal and is perfect for those adventurous enough—and who have the time—to travel here. Previously camping only, there are now more affordable teahouse routes that take you past stunning Himalayan vistas and into the heart of traditional cultures.