IMD Predicts Below-Normal Monsoon Rainfall for Bihar in 2026
Patna, Bihar is likely to experience below-normal rainfall during the upcoming southwest monsoon season from June to September 2026, according to the first phase of forecasts released by the India Meteorological Department (IMD). This prediction continues a concerning pattern, as data reveals the state has recorded below-normal rainfall in seven out of the last ten years.
Historical Rainfall Data and Normal Benchmarks
The normal rainfall for Bihar, defined as the 30-year average, is established at 992.2 millimeters for 2026. Official records from 2016 to 2025 highlight significant fluctuations. The year 2020 saw the highest rainfall at 1,244.9 mm, representing a positive departure of 24%. In stark contrast, 2022 recorded the lowest rainfall at just 661.8 mm, marking a substantial deficit of 33%. Most recently, 2025 continued the trend with below-normal rainfall of 681 mm, a negative departure of -31%.
Potential Impact on Agriculture and Water Resources
A deficit monsoon poses serious risks to Bihar's agricultural sector, particularly affecting Kharif crops such as paddy and jute, which rely heavily on consistent water availability during the growing season. Reduced precipitation could lead to lower crop yields, impacting farmers' livelihoods and food security in the region.
Furthermore, insufficient rainfall may limit the recharge of small water bodies and groundwater reserves, raising significant concerns over water availability in the subsequent months. A weaker monsoon could also affect temperature regulation due to diminished cloud cover and easterly winds, potentially prolonging heatwave conditions across the state.
Uneven Rainfall Distribution Across Districts
Rainfall distribution has been highly uneven across Bihar's districts over the past decade. Kishanganj consistently records the highest rainfall, benefiting from its proximity to the Himalayas. Conversely, districts including Arwal, Saran, Sheohar, Muzaffarpur, and Lakhisarai have experienced the lowest rainfall levels, exacerbating regional disparities in water access and agricultural productivity.
Meteorological Factors Influencing Rainfall Patterns
Meteorologist Sanjay Kumar of IMD Patna explained that Bihar's monsoon rainfall largely depends on low-pressure systems forming over the north Bay of Bengal. In recent years, these systems have frequently shifted towards coastal states like Odisha, reducing precipitation in Bihar. Additional influencing factors include:
- The potential development of El Nino conditions during the monsoon season, which could delay and weaken rainfall.
- Climatic conditions over the Indian Ocean.
- Slightly below-normal snow cover in the Northern Hemisphere in recent months.
Looking Ahead: Updated Forecasts and Monitoring
The IMD is expected to issue an updated monsoon forecast later this month, providing more detailed insights into the anticipated rainfall patterns. Continuous monitoring of these meteorological factors will be crucial for farmers, policymakers, and water resource managers to implement adaptive strategies and mitigate the adverse effects of a potential rainfall deficit.
