It can be hot during peak afternoon hours but not exhausting. When in Kathmandu apart from Pashupatinath Temple and Darbar Square, visit Bhaktapur and the royal museum. Thamel is the tourist place, heaps of lounges, I recommend Kathmandu Guest House for stay and New Orleans for dinner although Jazz Upstairs in another location has it's own charm. Asan is the local market & must visit. In Pokhara apart from the temple, sunrise at Sarangkot witnessing mighty Annapurna range is total magic. Mountain museum in Pokhara is something you will regret missing. There is also Shiva cave temple and other caves to explore by. If time allows Chitwan National Park, Bandipur & Lumbini are also good places to visit in Nepal.
May Weather Averages for Kathmandu, Nepal. However May is considered even hotter as, during this period, even the night time temperatures stay quite high. The average day time temperatures are around 30°C (86°F) whereas during the night the average minimum temperatures drop to around 20°C (68°F).
Kathmandu and Pokhara both are valleys and normally hot. Visit all 7 UNESCO World Heritage Sites in Kathmandu and local Thamel Market. Enroute Manakamna Temple thru Ropeway. In Pokhara Sunrise point at village Sarangkot, Devi's Fall, Phewa Lake, Shanti Stupa, Seti River Gorge.
Its hot only in afternoon time....otherwise it's a Himalayan country...in..pokhra you can visit phewa lake ,hire a boat and visit a temple on a little island in between the lake ...you can visit Devi's fall , do a Annapurna trekking..on the way to KATHMANDU there is a temple named Manokamna Temple ....there is Asia's largest ropway...in Kathmandu you can visit Pashupatinath Temple, Budhaa Stupa, Bhagwaan Neelkanth Temple and Trimoorti Temple. For shopping you can go Thamal market situated in Kathmandu. if you like suggestions upvote it and thaks in advance