Seasons for Trekking in Nepal

Trekking in Nepal can be undertaken throughout the year with four distinct seasons each with different attractions to offer:
Spring (between March – May): The spring, which is considered as one of the most colorful seasons of the year, that offers an odd possibility for the trekkers to be hit by the shower of life-giving rain. The temperature is mildly warm in low lands while moderate in higher altitudes. Warm weather brings more trekkers though not as many in autumn. The dispiriting fog that keeps moving the elevation, unpleasant afternoon winds,etc. may not encourage one to trek while in the other hand the fog and the wind may be the main attraction for others. It is also the time for flowers to blossom. The astonishing views of the national flower of Nepal – rhododendron while in the trek takes all the fatigue of the trekkers away.
Summer (between June – August): This is also called the monsoon season in Nepal. It is hot, hazier, increasingly unsettled and quite wet at times. It rains almost every day with occasional thunderstorms in the evenings that bring pleasantness around. Despite being wet, the mornings are often clear, wild flowers and butterflies are abundantly seen and green is everywhere. This is the right season for the trekkers to go high up but only by being well prepared for the rain.
Autumn (between September – November): This is the best tourist season in Nepal with tantalizing mountain views and a clear sky. The Annapurna and Everest trails remain busy and there is race among porters and guides to look up the lodges during the season.Summer receives a farewell and winter is all ready to come in. The weather is highly pleasant and so are the mountain views. This is the peak season for trekking as mountain views are guaranteed so you better book your flight in advance. Nepal celebrates the biggest Hindu festival Dashain followed by Tihar in this very season so it is also known the season of festivities. Witness the entire country smile as the nation sinks itself into the blessings and enchantment of dashain and the multicolored lights of tihar. 
Winter (between December – February): The weather is cool and the sky is clear with occasional snowfalls at higher elevations. Most part is dry, settled, and colder. This is a good season to trek in lower elevation. The mornings and nights are cold and the days are comparatively warm when sunny.