Nepal has four climatic seasons.
Spring (between March and May): The temperature is mildly warm in low lands while moderate in higher altitudes with plenty of opportunities to have a tryst with the mountain views. It is also the time for flowers to blossom and the national flower of Nepal – rhododendron sweeps the ascending altitudes with its magnanimous color and beauty. It is the best time to visit and trek; spring brings warm weather.
Summer (between June and August): This is also the monsoon season in Nepal. The weather is hot and wet at times. It rains almost every day with occasional thunderstorms in the evening. The rain spreads the pleasantness around with lush green vegetation.
Autumn (between September and November): This is the best tourist season in Nepal with the summer gone by and the winter to set in. The weather is highly pleasant so are the mountain views. Thousands of people hit the trails in the Everest and Annapurna regions. This is also the season of festivities as Nepal celebrates the biggest Hindu festivals Dashain followed by Tihar.
Winter (between December and February): The weather is cool and the sky is clear with occasional snowfalls at higher elevations. This season is good for trekking in lower elevations. The morning and night are cold and the days are warm when sunny.