Introduction
Uttar Pradesh falls within the sub-tropical climate zone. The climate here is characterized as tropical monsoon type or humid sub-tropical type with a dry winter. In the Terai region, moisture persists, while in the southern plateau region, there is no moisture during the summer season. Based on rainfall, topography, and soil characteristics, nine agro-climatic regions have been identified in Uttar Pradesh.
Climate of Uttar Pradesh
The climate of India has been categorized based on various criteria, including the climate of Uttar Pradesh. This division can be observed through both general and specialized classifications.
General division
Uttar Pradesh is mainly divided into two climatic regions.
- One, the humid and hot regions;
- Two, simple humid and hot regions.
The humid and hot regions are divided into Terai region ( 120-180 cm annual rainfall ) and Eastern Uttar Pradesh ( average annual rainfall up to 100-120 cm ).
The plain area under the ordinary humid and hot region where the average annual rainfall is 80-100 cm. The amount of rainfall is less in the western plains and the plateau and hilly regions of Bundelkhand. The reason for this is that the amount of humidity decreases on going from east to west and from north to south in the state.
According to Koeppen, U.P. has ‘monsoon type with dry winter’ or ‘monsoon with dry winter’ type of climate. Koeppen abbreviate it as Cwg.
- This is also known as the ‘Gangetic plain type climate’ and the ‘Mesothermal climate’.
According to Thornthwaite, U.P. has ‘dry sub-humid’ type climate. Thornthwaite abbreviate it as C1.
According to Trewartha, U.P. has ‘humid sub-tropical’ type of climate. He abbreviate it as Caw.
Specialised division : on the basis of rainfall
Pro. Stamp and Dr. Qazi Syed Ahmed have divided the climate of India on the basis of rainfall, according to which two types and five sub-types of climatic regions are found in Uttar Pradesh –
- humid and hot zone
- Tarai region
- Eastern Uttar Pradesh
- normal humid and hot zone
- Intermediate plain region
- Western plain region
- Hilly plateau region of Bundelkhand
Terai region includes the districts of Saharanpur, Bijnor, North Moradabad, Rampur, Bareilly, Pilibhit, Lakhimpur, Bahraich, Gonda, Basti, Siddharth Nagar, Maharajganj, Gorakhpur, Deoria, Kushinagar etc. The average annual rainfall here ranges from 120 to 150 cm. The average temperature in this region is 18°C in January and 30°C in July.
Eastern Uttar Pradesh region ranges from 100 to 120 cm. In this sub-division, the amount of rainfall decreases on moving from east to west.
The intermediate plains include northern Prayagraj, Pratapgarh, Fatehpur, Rae Bareli, Sultanpur, Lucknow, Unnao, Kanpur, Hardoi, Farrukhabad and southern Shahjahanpur. The average annual rainfall of this region is 80 to 100 cm. Here the temperature is high in summer and the average temperature in winter especially in January is 15°C – 16°C. The amount of rainfall in this region decreases from east to west.
The western plains include districts of Agra, Mainpuri, Mathura, Etah, Aligarh, Badaun, Bulandshahr, Ghaziabad, Meerut, Muzaffarnagar, South Saharanpur etc. The average annual rainfall in this region ranges from 65 to 80 cm and the average temperature in winters ranges from 12°C to 14°C. In this region, the amount of rainfall decreases from east to west.
The Hilly plateau region of Bundelakhand includes districts of Lalitpur, Jhansi, Banda, Hamirpur, Mahoba, Jalaun, Chitrakoot, Southern Etawah, Southern Prayagraj etc. The average annual rainfall of this region is 80 to 100 cm. The average temperature in this region is 18°C to 19°C in winter and 40°C to 45°C in summer. On June 10, 2019, Banda recorded a temperature of 49.2°C. In this region too, the amount of rainfall decreases from east to west.
Seasons
Mainly three seasons are found in Uttar Pradesh –
- summer season,
- rainy season and
- winter season.
The Summer Season
As the sun moves towards the Tropic of Cancer, the temperature of the state starts increasing and reaches its highest point in June. At this time the Sun shines directly on the Tropic of Cancer.
The summer season in Uttar Pradesh is from mid-March to mid-June. The highest temperature is recorded in the state in May and June.
In summer, the average maximum temperature of the state ranges from 36°C to 39°C and the average minimum temperature ranges from 21°C to 23°C and the average temperature difference is 14°C.
Due to being closeness to the Tropic of Cancer, the temperature in Bundelkhand cities like Prayagraj, Kanpur, Fatehpur, Agra, Banda, Chitrakoot, Mahoba, Jhansi, Hamirpur, Jalaun, Lalitpur etc. reaches 40° to 47°C. In other words, due to its proximity to the Tropic of Cancer, highest temperature is found in the Bundelkhand region.
Maximum heat is experienced in Agra and Jhansi and minimum in Bareilly.
In this season, especially in the months of May-June, the westerly winds become intense, which are called ‘Loo’. Which lasts from 10 am to 5 pm and is very hot and dry which scorches the body. Dust storms often occur in the Ganges plains in the evening, their velocity sometimes ranges from 100 to 115 kilometers per hour.
Although the rainfall is very less in this season, still it receives rainfall from 10 to 25 cm.
The Rainy Season
The rainy season in Uttar Pradesh starts from the last week of June and lasts till October. The maximum rainfall in the state occurs in July and August.
The South-West Monsoon ( Purva ) arising from the Bay of Bengal enters from the eastern and south-eastern ends of the state through the plains of Bihar in the third-fourth week of June and moves further. This is called Purva.
Some part of this monsoon goes directly west while raining, but some part moves north and collides with the Himalayas and comes back again. Due to this retreating monsoon, there is a lot of rain in the Terai areas of the state.
Most of the rainfall in the state is received from the Bay of Bengal branch of the south-west monsoon i.e. from Purva. From this the state gets about 75-80% share.
About 83% of the rainfall in the state occurs between June and September and the remaining 17% is received from western disturbances in the winter season.
About 60% of the state’s total rainfall occurs in the months of July and August.
The withdrawal of monsoon from Uttar Pradesh starts in the month of October.
Uttar Pradesh receives nominal rainfall from the Arabian branch of the south-west monsoon, that too in the southern plateau regions.
There is variation in the amount of rainfall in different parts of the state. For example :
- Gorakhpur region receives maximum (184.7 cm) rainfall in the state.
- Mathura receives the lowest (54.4 cm) rainfall in the state.
- The average rainfall in the eastern plains is 112 cm.
- The average rainfall in the central plains is 94 cm.
- The western plains receive 84 cm of rainfall.
- The average rainfall in the southern hill-plateau region is 91 cm.
In the state, as we move south from the Himalayas or as we move from east to west, there is a decrease in the amount of rainfall. Similarly, there is a decrease in the duration of rainfall. In Gorakhpur where there is a possible period of rain for 56 days, in western Uttar Pradesh only 32 days.
About 83% of the state’s total rainfall occurs in this season ( from July to September ), the remaining rainfall ( ≈ 17% )occurs in winter ( western disturbance ) and summer ( cyclone ).
In the Rainy season, the average maximum temperature of the state is 32 to 34 °C and the minimum temperature is 25 °C and the average temperature difference is 7-8 °C.
The maximum flow in the rivers of the state remains only during the monsoon. Generally the most flood affected area is Purvanchal. The biggest flood in the state occurred in 1978 AD, due to which there was a huge loss of life and property.
The Winter season
The winter season in the state lasts from November to February. The temperature keeps falling continuously till January. January is the coldest month of the state.
There is a great difference in the temperature of different parts of the state in the winter season.
- In the southern hill and plateau regions, the average maximum temperature is 28.3 °C and the average minimum temperature is 13.3 °C.
- The average maximum temperature in the plains is 27.2 °C and the minimum temperature is 8.5 °C.
- The average winter temperature in the north-western districts is about 10 °C the lowest among all other regions. When there is snowfall in Uttarakhand, the cold in this region increases further.
In winter, the temperature of Uttar Pradesh increases from north to south.
Western Uttar Pradesh receives more than 10 cm of rainfall in winter due to the entry of cyclones coming from the Mediterranean region via Pakistan, which is beneficial for the Rabi crop. This is called Western Disturbance. The average number of these cyclones is between 3 to 5. These cyclones cause rainfall of 7 cm in the north-eastern regions and 5 to 7.5 cm ( least ) in the plateau regions.
Fog prevails many parts of the state are affected by fog. Fog is also beneficial for rabi crops. Sometimes the sun is not visible for many days in the lowlands due to fog. Due to this fog, the visibility decreases and there is difficulty in movement.