The climate of Uttar Pradesh is generally defined as tropical monsoon type.
UP has the following three predominant seasons:
- Winter Season - November to February
- Summer Season - March, April and May
- South-west Monsoon - June, July, August, September and October
Retreating Monsoon season, although existent, has a very negligible effect in Uttar Pradesh and only occasional mild showers are experienced in winter. Some of these showers are not even due to the Monsoon but due to western disturbances.
The primary temperature, rainfall and wind features of the three Distinct Seasons of U.P. can be summarized as below:
- Summer (March–June) : Hot & dry (temperatures rise to 45°C, sometimes 47-48°C); low relative humidity (20%); dust laden winds.
- Monsoon (June–September) : 85% of average annual rainfall of 990mm. Fall in temperature 40-45° on rainy days.
- Winter (October–February) : Cold (temperatures drop to 3-4°C, sometimes below -1°C); clear skies; foggy conditions in some tracts.
Given significant climatic differences, U.P. has been divided into two meteorological sub-divisions - U.P. East and U.P. West.
Temperature varies from 0 to 46°C.High temperatures of around 50°C have been recorded in Gonda district of U.P. Such a wide range of temperature fluctuations in most parts of the state, it can lead to either cold waves or heat waves.
It rains over most of U.P. with very few arid or semi-arid patches. Snowfall is negligible but hail-storms, frost and dew occur often in U.P. The type of rainfall that U.P. receives is orographic, cyclonic and convectional.
Rain
Primarily a summer phenomenon, the Bay of Bengal branch of the Indian Monsoon is the major bearer of rain in most parts of U.P. It is the South-West Monsoon which brings most of the rain here, although rain due to the western disturbances and North-East Monsoon also contribute small quantities towards the overall precipitation of the state.The rain in U.P. can vary from an annual average of 170 cm in hilly areas to 84 cm in Western U.P.Given the concentration of most of this rainfall in the 4 months of Monsoon period, excess rain can lead to floods and shortage to droughts. As such these two phenomenons of floods and droughts are a common recurrence in the state.
Floods in U.P.
Floods are a known hazard of U.P. due to overflowing of its main rivers like Ganga, Yamuna, Ramganga, Gomti, Sharda, Ghaghra, Rapti and Gandak.Estimated annual losses due to floods in U.P. is Rs. 4.32 billion (US$70 million).Major flood management efforts have been undertaken to mitigate the risk. Most of these floods occur due to the Monsoon rains and overflowing of rivers during the rainy periods. Year 2010 witnessed one such year of flooding in U.P
Droughts in Uttar Pradesh
Shortage of rain during the highly variable Monsoon season can cause droughts in U.P. leading to severe loss to man and property. Recent 2002 and 2004 drought related financial estimates have been reported to be Rs. 75.4 billion(US$1.2 billion) and Rs. 72.92 billion (US$1.2 billion). The recurrence of a major deficiency in annual rainfall follows a 6-8years cycle in Eastern U.P. whereas in Western U.P., it is a 10 years cycle.
In summers, hot winds called loo all across U.P. These are dust-laden and quite damaging.In winters, dry and rainless winds blow across the state. Fog may also form in parts of U.P.