Nepal is broadly temperate, with four main seasons centered around the summer monsoon. When considering the best time to visit, it’s worth considering that the majority of visitors, prioritizing mountain visibility, come in the autumn peak season (late Sept to late Nov), when the weather is clear and dry, and neither too cold in the high country nor too hot in the Terai. With the pollution and dust (and many bugs) washed away by the monsoon rains, the mountains are at their most visible, making this an excellent time for trekking. Two major festivals, Dashain and Tihar, also fall during this period. The downside is that the tourist quarters and trekking trails are heaving, prices are higher and it may be hard to find a decent room.
Winter is mostly clear and stable. It never snows in Kathmandu, but mornings can be dank and chilly there This is an excellent time to visit the Terai. The winter months from December to February tend to be mild in the daytime but can become very cold at night, especially in the mountains. January is the coldest month of the year and although Nepal’s cities are chilly, as there is no snow it is easy to explore the sights. If you are planning to visit Nepal during Christmas, you can go on short tours like Ghandruk Ghorepani trek, Namche Bazaar Trek. Besides, if you can tolerate extreme cold then mountains are always calling you.
Spring (Feb to mid-April) is the second tourist season, with its warmer weather and longer days. Spring season continues in Nepal from March till May. The temperature is about 22℃ with slight rainfalls at night and clear skies in the morning. This is the time for new buds and flower blossoms. You can enjoy adventure activities like Paragliding, Bunjee, Rafting, Trekking in spring weather. Rhododendron blossoms with exuberant beauty in the high hill will leave you spellbound. It is one of the major tourist seasons in Nepal.
Nepalese welcome the monsoon, the timing of which may vary by a few weeks every year, but typically begins in mid-June and peters out in the last weeks of September. The fields come alive with rushing water and green shoots, and this can be a fascinating time to visit, when Nepal is at its most Nepali: the air is clean, flowers are in bloom, butterflies are everywhere and fresh fruit and vegetables are particularly abundant. But there are also drawbacks: mountain views are rare, leeches come out in force along the mid-elevation trekking routes, roads and paths may be blocked by landslides, and flights may be cancelled.
From September the climate begins to change as the country welcomes autumn, which lasts from October to November. These months are much drier with pleasant temperatures in the day time and good visibility, leading to this being peak season for visitors. During this season of paddy harvest, nature ripens in yellow. It is the time after monsoon rain washes the whole surrounding. You can enjoy panoramic mountain views during this time. It is the popular trek season in Nepal where the sky is clear, blue and the weather clear.