Mod 2: Rainfall Patterns & Temperature Trends

Shifts in rainfall distribution and extreme weather events directly reflect the accelerating impact of climate change. Bihar experiences precipitation across all four seasons: Winter, Summer, South-West Monsoon, and North-West Monsoon (post-monsoon rains).

Rainfall Dynamics & District Extremes:

• The long-term average annual rainfall recorded in Bihar across the extended period (2011–2024) stands at 1,004.6 mm.
• In 2022-23, Bihar recorded total rainfall of 849.1 mm, falling substantially below the long-period average (LPA) and impacting agricultural output.
• Annual Fluctuations: In 2013, Bihar experienced a record minimum rainfall (only 77.0% of the long-term annual average), whereas in 2021, maximum rainfall was registered at 140.7% of the annual average.
• District-wise Extremes: According to the latest survey figures, Kishanganj recorded the highest annual rainfall in the state (2,127.5 mm), while Kaimur registered the lowest annual rainfall (711.2 mm).

Temperature Trends & Heatwave Extremes:

• Bihar predominantly experiences a subtropical climate with harsh winters and hot summers.
• Surface air temperature trends:
  • The annual average temperature in Bihar rose from 21.2°C (2017) to 24.7°C (2023).
  • In Patna, the annual average surface air temperature in 2021 was 24°C (0.1°C above LPA).
  • In 2022-23, Bihar's statewide annual average surface air temperature was 24.7°C, with an average minimum of 7.1°C.
  • In 2021, the state average minimum temperature was 30°C, while the average maximum reached 42.3°C.
• Global warming has intensified heatwave ('loo') severity during summer months, with peak mercury levels frequently scaling 45°C to 46.4°C.