Critical analysis of rainfall and
possible drought period
in the country
Dr Teekam Singh
Principal Scientist
Division of Agronomy, IARI, New Delhi -12
teekam@iari.res.in
Rainfall Patterns in India
• Monsoon-Driven Climate
• India has a tropical monsoon climate with distinct wet and dry seasons.
• Rainfall is highly seasonal, with 75-80% occurring during the Southwest
Monsoon (June–September) with Annual Average: ~1,150 mm
Major Rainfall Seasons
• Southwest Monsoon (June–Sept)
Originates from Arabian Sea & Bay of Bengal.
Covers the entire subcontinent.
Critical for agriculture.
• Northeast Monsoon (Oct–Dec)
Affects southeastern India, especially Tamil Nadu and coastal Andhra
Pradesh.
Lesser contribution compared to southwest monsoon but regionally vital.
• Pre-monsoon (March–May) & Post-monsoon (Oct–Nov)
Sporadic convectional rainfall and cyclonic activity.
Erratic distribution of rainfall
Western Ghats & Northeast India
• Extremely high rainfall (>2000 mm
annually).
• Examples: Mawsynram, Cherrapunji.
Northwest India (Rajasthan, Gujarat)
• Arid and semi-arid with <500 mm
rainfall.
Central India (MP, Chhattisgarh)
• Moderate rainfall; critical food-
producing belt.
Peninsular Plateau
• Moderate but uneven rainfall due to
topography.
Unequal distribution of rainfall leads to
floods in some areas and droughts in
others within the same year.
Spatial Variability in Rainfall
Extreme Rainfall (>300 mm/year): Western Ghats and Northeast India — Mawsynram
(Meghalaya) receives ~11,872 mm annually, ranking among the wettest places on Earth
Heavy Rainfall (200–300 cm): Eastern India, particularly West Bengal, Assam, Tripura,
Odisha, Bihar, and the sub-Himalayan belt
Moderate Rainfall (100-200 cm): Central India and leeward sides of Ghats; includes
parts of Madhya Pradesh and Andhra Pradesh
Scanty Rainfall (50-100 cm): West-central India (Punjab, Haryana, Rajasthan,
Maharashtra, Karnataka)
Desert & Semi‑Desert (<50 cm): Rajasthan, Gujarat, Jammu & Kashmir, Ladakh
Rainfall Distribution Challenges
Temporal Variation: Rainfall is highly seasonal—some regions get nearly all months’
rainfall within 1–2 months, especially northwestern India
Spatial Variation: Significant disparities among states, even districts—e.g., some may
see >2000 mm, others <500 mm.
Extreme Events: Trends show more heavy rainfall events (≥ 50 mm/day) in regions like
Gujarat, Rajasthan, Assam, Meghalaya—while moderate rainfall events have declined in
central Indi
Seasonal and high intensity rainfall for short period (June–Sept), which challenges
water conservation.
Monsoon Irregularities in India
Delayed Onset
• Expected Onset: Around June 1 (Kerala).
• Irregularity: Sometimes arrives later than usual, delaying the sowing of crops.
• Impact: Affects the Kharif cropping season, leading to reduced yields and food
insecurity.
Early Withdrawal
• Monsoon usually withdraws by end of September, but early withdrawal reduces
rainfall during the crucial later stages of crop growth.
• Leads to water stress in rain-fed areas.
Breaks in the Monsoon
• Periods of no or minimal rainfall lasting for a few days to weeks, especially in
July and August.
• Caused by shifts in the monsoon trough or presence of dry air.
• Severely affects crop growth during key developmental stages.
El Niño and La Niña Effects
El Niño and La Niña are opposing phases of the El Niño–Southern Oscillation
(ENSO) cycle, which originates in the Pacific Ocean but has significant global impacts
— especially on India’s monsoon.
El Niño
• Warming of the central and eastern Pacific Ocean.
• Weakens the Indian monsoon winds and suppresses rainfall.
• Associated with heatwaves, droughts, and forest fires.
• Reduces crop yield, especially rice, pulses, and sugarcane.
La Niña
• Cooling of the central and eastern Pacific Ocean.
• Strengthens monsoon winds, often leading to increased rainfall in India.
• Increased chances of landslides, floods, and cyclones.
• Boost yields but also increase flood risks and pest outbreaks.
Shifting Monsoon Patterns
• Onset and withdrawal dates becoming more erratic.
• Monsoon season is shortening, but rainfall is becoming more
intense.
• Increases risk to food security, water availability, and disaster
preparedness.
Monsoon irregularities in India reflect a growing concern due
to climate change and environmental degradation. They affect
agriculture, water management, disaster risk, and the economy.
Addressing these irregularities requires:
• Better forecasting systems
• Improved irrigation and water storage infrastructure
• Promotion of climate-resilient crops and farming practices
Rainfall comparison and deviation
Possible drought periods during monsoon season
• June: Delayed onset or poor rainfall impacts sowing (especially
in central and northwestern India).
• July–August: Breaks in monsoon (i.e., temporary dry spells
lasting 10–20 days) lead to stress during crucial crop growth
periods.
• September: Early withdrawal of the monsoon reduces late-season
rain, crucial for rice and sugarcane in eastern and southern India.
Post monsoon
• Hydrological droughts may emerge if groundwater and
reservoirs are not replenished after a weak monsoon.
• October–December (Northeast Monsoon) failure especially
affects Tamil Nadu, south Andhra Pradesh, and Kerala, leading to
regional droughts.
Historical Drought Years in India in 21st century
Year Monsoon Deficit Impact
Severe drought across 29% of land; major
2002 ~19% below normal
crop losses
One of the worst in 30 years; impacted food
2009 ~22% below normal
prices
Linked to El Niño; two consecutive drought
2015 ~14% below normal
years in many areas
Severe drought in Tamil Nadu and South
2018 Weak NE monsoon
Interior Karnataka
Some areas (e.g., Eastern UP, Bihar)
2023 Regional shortfalls experienced dry spells despite national
average rainfall being near normal
Case Study – 2015 South India Drought
Worst rainfall deficit in Tamil Nadu in over a century.
Failed Northeast Monsoon; crop losses over ₹10,000 crores.
Drinking water scarcity in Chennai and surrounding districts.
Led to greater focus on urban rainwater harvesting and lake
restoration.
Case Study – 2019 Monsoon Delay
Monsoon onset delayed by 7–10 days.
Early-season crop sowing affected in Gujarat and Maharashtra.
Mid-season surge led to localized floods.
Highlighted the need for adaptive crop calendars and real-time
agromet advisories.
