Climate of West Bengal

The climate of West Bengal is varied, with tropical savannahs in the southern portions of the state, to humid subtropical areas in the north. Temperatures vary widely, and there are five distinct seasons. The area is vulnerable to heavy rainfall, monsoons, and cyclones. There are some mountains in the area which are generally cold all year round.



Seasons
There are five main seasons in West Bengal: spring, summer, rainy season, a short autumn, and winter.

Spring
Spring is considered the most pleasant season over the plains of West Bengal and lies from mid-February to mid-March and is also the time where Holi is celebrated. Temperatures range between 20 °C – 30 °C and no rainfall. Though occasional rain or light showers are witnessed due to Western disturbances in North India.

Summer
The summer season is observed from March to May in most of Bengal.

Temperature
In Bengal, summers can be extremely hot and have high humidity. The plains of South Bengal have a daily maximum temperature around 35–38 °C. It can also exceed 40 °C. The western highlands experience a dry summer like northern India. During the day, the temperature ranges from 38 to 42 °C, though it can reach or exceed 45 °C. In summer, the plains of North Bengal are generally cooler than the west and south. In this area, the daily maximum temperature varies from 26 to 32 °C. It occasionally crosses 35 °C. The minimum temperature in summer is approximately 18–22 °C. The Darjeeling hill region is the coolest area in summer. Here, the daily highest temperature is 15–25 °C.

Period
In mid-June or early July, the monsoon season starts. It continues until the end of September or early October.

Temperature
In most places, the temperature drops as cloud cover increases. This is less true for the mountains and the Terai Dooars plains, where temperature gradually increases until August.

The maximum temperature of South Bengal's plains and western highlands is 32 °C, 31 °C in North Bengal plains and around 19–20 °C in mountains. Sometimes when the sky gets clear, the temperature rises suddenly. This is known as a monsoon break. This occurs mostly in North Bengal plains and in mountains in July and August when the temperature soars over 36 °C and 24 °C respectively.

Rainfall
Most of the annual rainfall occurs during the monsoon period. Heavy rainfall above 250 cm is observed in the Darjeeling, Jalpaiguri, Alipurduar and Cooch Behar district. Later, blowing westwards, the winds cause average rainfall of 125 cm in the northern plains and western plateau region.

Period
Autumn lasts for two months, October and November.

Temperature
In autumn, the southwest monsoon wind returns and clears the sky. So, the state gets enough sunshine to be warm in the day and releases a lot of heat to be cool at night.

At this time, a maximum temperature of 30–33 °C is felt over the plains and 17–19 °C in mountains. The minimum temperature is normally around 19–22 °C in plains and 6–11 °C in mountains. Sometimes, cold waves blow over the state in autumn.

Rainfall
In autumn, the southwest monsoon wind returns, and the northeast monsoon wind enters West Bengal. Due to their collision in Bay of Bengal, some cyclones are created. The cyclones cause some rainfall in the state.

Period
The winter season usually starts in December and ends in February.

Temperature
In winter, a mild temperature is observed over the plains. The maximum temperature goes to 23–26 °C and the minimum temperature is 9–15 °C in plains of the state. The maximum and minimum temperature in the mountains range from 0–12 °C. Higher regions of the Darjeeling Himalayas get heavy snowfall during winter.

The temperatures of the western highlands at night can drop 7–9 °C,  4–7 °C in Siliguri, Jalpaiguri, Coochbehar plains    and 10–11 °C in Kolkata    when cold waves blow. Darjeeling's temperature can drop below freezing point.

Rainfall
Winter is generally dry. Most days are sunny. Occasionally, slight rainfall occurs because of conditions in northwest India. These are known as western disturbances.

Extreme temperatures
Sources: India Meteorological Department

Record high temperatures
The chart below shows the highest recorded temperatures in individual stations, for all months in West Bengal, with place and date.

Record low temperatures
The chart below shows the lowest recorded temperatures in individual stations, for all months in West Bengal, with place and date.

Record low temperature in the plains
The chart below shows the lowest recorded temperatures in individual stations in the plains, for all months in West Bengal, with place and date.

Extreme Rainfall
The chart below shows the maximum recorded rainfall in individual stations (observatories) in the state, for all months, with place and date.

Rainfall
Annual rainfall varies in different parts of the state. North Bengal receives the highest rainfall, 200 to 400 cm. In the coastal areas rainfall is about 200 cm, in the Ganga plain and in the central part of the state rainfall is about 150–200 cm, and in the western plateau region the amount of rainfall received is about 100 to 125 cm. Drought is a common phenomenon in the Bankura and Purulia districts. Rainfall that occurs in the summer months often brings about heavy storms called Kalbaishakhi.

Mountainous region
Because of the high altitude, mountainous parts of Darjeeling and Jalpaiguri experience a cool temperate and climate. The average temperature in summer is about 15 °C, and winter temperature is about 2 °C. Snowfall occurs in some parts of this region. Being obstructed by the Himalayas, the region receives heavy rainfall. Due to the scenic beauty and temperate climate of the region, a huge number of tourists visit the areas. Here Kalimpong is another hill station that is visited by many tourists in all seasons for its scenic beauty and the average cool temperature throughout the year.