June heralds the arrival of the monsoon in Nepal. The rains hit the east of the country first, early in the month. Hot air brought in from the south and east is laden with moisture from the Indian Ocean and when it hits the cooler air of Nepal's hills and mountains it drops it, often torrentially. Consequently, June is not the best month of the year to visit Nepal.
Unfollow the herd - travel in Nepal during June and enjoy fewer crowds, better availability, and help to spread the economic benefits of tourism.
It's low season for tourists in June, so if you can brave the downpours and don't mind getting up a little early, June is not a bad time to wander around ancient temples and explore Nepal's cultural treasures. Humidity levels on the plains and in Chitwan are high, so it can be tough going during the day here with temperatures in the mid-30s. It's high water season and rivers like the Trisuli are full, ideal for more adventurous white water rafting. Trekking isn't totally out of the question, but you will get wet at times and the mountains are often shrouded in cloud; trails can be muddy and the extra moisture tends to mean that leeches are a problem. However, the rain tends to fall mainly at night, which means the mornings can dawn clear and beautiful. There are few other tourists around in June and the temperatures at altitude are pleasantly warm, in the low 20s.