Weak monsoon, heat spell likely to affect Bihar’s kharif sowing

Meanwhile, the India Meteorological Department (IMD) has forecast thunderstorms accompanied by gusty winds of 30-50 kmph across several parts of Bihar over the next week

A delayed and weak southwest monsoon, coupled with above-normal temperatures and deficient rainfall across large parts of Bihar, has begun affecting kharif sowing, with agricultural experts warning of lower crop yields if rainfall does not improve soon.

Girls covering their faces during a hot summer day in Patna. (Santosh Kumar/HT)

The India Meteorological Department (IMD) has forecast thunderstorms accompanied by gusty winds of 30-50 kmph across several parts of Bihar over the next week. Heavy rainfall is likely at isolated places in Aurangabad, Bhabhua and Rohtas on July 6; Araria, Kishanganj and Supaul on July 7-8; and Bhagalpur, Katihar and West Champaran on July 11. However, rainfall is expected to remain confined to isolated or a few places in most regions, indicating that widespread monsoon activity is yet to set in.

The Bihar Mausam Sewa Kendra (BMSK) has also warned of high heat and humidity-induced discomfort over the next two days in East Champaran, West Champaran, Gopalganj, Saran, Siwan, Muzaffarpur and Vaishali districts. The state’s highest temperature in the past 24 hours touched 40.9°C at Chanpatia in West Champaran and Birpur block of Begusarai district, while the highest rainfall recorded was only 20.5 mm at Mainatand in West Champaran.

The BMSK’s daily weather bulletin said no significant rainfall was recorded in Patna during the previous 24 hours, with the state’s highest rainfall of 20.5 mm being reported from Mainatand in West Champaran.

State capital Patna received smart showers on Sunday evening. The weather forecast further said Patna is likely to witness thunderstorms accompanied by lightning and gusty winds of 30-40 kmph at isolated places on July 6, while similar conditions are expected across most parts of Bihar, including Patna, on July 7. No heavy rainfall warning has been issued for Patna during the forecast period of July 5-11, although isolated thunderstorms may continue.

Rainfall has remained below normal in several districts, with only scattered light to moderate showers reported during the past 24 hours. The highest recorded rainfall of 20.5 mm in West Champaran underscores the absence of widespread monsoon precipitation across the state.

According to the IMD, Bihar recorded a 55% cumulative rainfall deficit, having received 99 mm of rainfall against the normal 219 mm up to 8.30am on July 5.

The rainfall deficiency was widespread, with all 38 districts recording below-normal rainfall. Of these, 38 districts fell in the “large deficit” category, receiving 60% or more less rainfall than normal. Several districts, including Gopalganj, Siwan, Muzaffarpur, Sheohar, Samastipur, Madhepura, Begusarai, Khagaria, Bhagalpur, Banka, Munger, Lakhisarai, Sheikhpura, Nalanda, Buxar, Rohtas, Aurangabad, Arwal and Gaya, recorded no measurable rainfall, resulting in a 100% deficit.

Among the remaining districts, East Champaran, Patna, Kaimur and Jehanabad reported 99% rainfall deficiency, while Araria, Darbhanga, Nawada and Jamui recorded 97% deficits. Saharsa registered a 95% deficit, followed by Madhubani (94%), Vaishali and Bhojpur (93%), Saran (92%), Katihar (91%), Sitamarhi (85%), Supaul (83%), Purnea (81%) and West Champaran (79%), according to IMD report.

The IMD data indicates that despite isolated showers in a few pockets, Bihar continues to face an acute monsoon shortfall, with virtually the entire state experiencing severe rainfall deficiency.

The sluggish monsoon has delayed paddy transplantation and affected germination of kharif crops, particularly in rainfed areas. Inadequate soil moisture has also increased irrigation demand, putting additional pressure on groundwater resources and exposing crops to heat stress during critical vegetative stages.

Rakesh Kumar, senior scientist, Crop Research Division, ICAR Research Complex for Eastern Region, Patna, said El Niño weakens the Indian summer monsoon by disrupting the Walker Circulation (a large-scale, east-west atmospheric air current across the tropics), resulting in below-normal rainfall, higher temperatures and increased evapotranspiration.

Kumar said the weather pattern delays sowing and weakens germination of kharif crops, especially paddy, while moisture stress during vegetative and reproductive stages reduces photosynthesis and grain filling. It also raises irrigation demand, depletes groundwater and increases the risk of heat stress and pest attacks.

He said Bihar typically witnesses a 10-20% decline in overall kharif productivity during a moderate to strong El Niño year, with losses rising to 20-40% in districts experiencing severe monsoon failure and limited irrigation. Crop-wise, paddy yields may decline by 10-30%—and by over 40% under severe drought in rainfed areas—while maize production could fall by 10-25% and pigeon pea, other pulses and oilseeds by 10-20%, if rainfall deficiencies persist, said Kumar.