Nepal Weather and Climate

Nepal has tremendous variation in climate. Its latitude is about the same as that of Florida so Terai land up to 500 meters (1,640 ft) has a fully tropical climate, with a subtropical zone extending up to 1,200 meters (3,937 ft) which is the lower limit of frost in winter. Warm temperate climates prevail from 1,200 to 2,400 meters (3,937 to 7,874 ft) where snow occasionally falls. Then there is a cold zone to 3,600 meters (11,811 ft) (tree line), a subarctic or alpine zone to 4,400 meters (14,436 ft) and fully arctic climate above that. Precipitation generally decreases from east to west with increasing distance from the Bay of Bengal, source of the summer monsoon. Eastern Nepal gets about 2,500 mm (98.4 in) annually; the Kathmandu area about 1,400 mm (55.1 in) and western Nepal about 1,000 mm (39.4 in). This pattern is modified by adabiatic effects as rising air masses cool and drops their moisture content on windward slopes, then warm up as they descend so relative humidity drops. Annual precipitation reaches 5,500 mm (216.5 in) on windward slopes in the Annapurna Himalaya beyond a relatively low stretch of the Mahabharata Range. In rain shadows beyond the high mountains, annual precipitation drops as low as 160 mm (6.3 in), creating a cold semi-desert.

Best season
Best times of the year for river running in Nepal are September through to November. In September, early October the rivers are running high with the Monsoon run-off whereas in October, the weather is settled, and this is one of the most popular times for rafting and kayaking in Nepal due to warm water and long hot days, perfect for the river and with dropping river flows time it is time to graduate to some steeper runs. From June till August the Monsoon rains arrive and the rivers hold ten times their low flows, and can flood with 60 - 80 times these flows.

Glance of Jungle Safari