The climate of Sikkim can be termed as temperate in broad terms. Sikkim enjoys the five seasons of summer, winter, monsoon, autumn and spring. Sprawled in an area of 7,096 km², Sikkim lengthens from an altitude of 280 m (920 ft) to 8,585 m (28,000 ft). With such varied altitudes, the state observes tropical, temperate and frigid climate in different regions. In the southern part, the weather is usually sub-tropical, whereas in the north, it is generally tundra.
However, the colonized regions are dominated by temperate climate,
where temperature rarely goes 28 °C maximum in summers and drops
below 0°C in winters. The average annual temperature for the major
part of Sikkim is recorded 18°C (64 °F) approx. During the
months of March - May, the sun shines at its best in the state of
Sikkim. The weather remains wintry and humid, since it rains most of the
Monsoon prevails from late-June to early-September. During Monsoons,
landslide is a common sight all the way through Sikkim. Being located in
hilly region, Sikkim is prone to landslides. The weather also becomes
humid and sultry, due to uncertain rain showers right through the year.
Autumn stays from September to October providing a nice time for
tourists to visit the state.
In India, Sikkim is one amongst the few states that receive regular
snowfall. The snowline of Sikkim is approx. 6,000 meters. The high
altitude in the northern region permits the temperature to drop below
-40°C in winters. The proper winter season starts from late
December till February, when the state gets too cold and damp due to
erratic rain showers. During winters, Sikkim also gets a covering of
deep fog, making transportation very risky.