The north is drying while south is getting wetter. Image Source: Ashwin Arun Yadav, Wikimedia Commons, CC BY-SA 4.0. Image for representation purposes only.
India’s rainfall patterns are changing, and the shifts are not the same across the country. While large parts of northern India are becoming hotter and drier, peninsular India is experiencing wetter conditions. Parts of Maharashtra, particularly Vidarbha and Marathwada, are exceptions to this trend, with rainfall patterns shifting towards drier climate zones.
These changes are taking place against a background of rising global temperatures. The Intergovernmental Panel on Climate Change (IPCC) estimates that global average surface temperatures have increased by approximately 1.1°C above pre-industrial levels. Recent decades have been the warmest in recorded history, with rising temperatures affecting regional climates, water cycles, ecosystems and livelihoods.
India has also experienced an average temperature increase of approximately 0.7°C over the past 120 years due to greenhouse gas induced warming, human generated aerosols and other factors. Both daytime and nighttime temperatures have risen. Such long-term changes can alter climate zones, which are defined by temperature and rainfall patterns, and influence agricultural and ecological landscapes.
A recent open access study by the India Meteorological Department (IMD) examines how these changes are reshaping the country’s climate zones. The findings point to significant shifts in rainfall patterns that could affect agriculture and highlight the importance of planning for long-term climate resilience.
The study , titled Identifying the climate zone shifts of Indian meteorological subdivisions: insights from historical records, was published in the journal Mausam. It analyses changes in climate zones across Indian meteorological subdivisions between 1951 and 2020, using IMD gridded temperature and rainfall data.
The researchers examined four broad geographical regions: Northwest India, Central India, Northeast India and Peninsular India.
Northwest India includes Haryana, Himachal Pradesh, Punjab, Rajasthan, Uttar Pradesh, Uttarakhand, Chandigarh, Delhi, Jammu and Kashmir, and Ladakh. The region spans the Western Himalayas, the Indo Gangetic Plain and the Thar Desert. Central India covers Madhya Pradesh and Chhattisgarh, while Northeast India includes Assam, Arunachal Pradesh, Meghalaya, Nagaland, Manipur, Mizoram, Tripura and Sikkim. Peninsular India comprises Maharashtra, Karnataka, Andhra Pradesh, Telangana, Tamil Nadu and Kerala.
The analysis considered seven climate subclasses: Tropical Monsoon, Tropical Savannah, Arid Desert Hot, Arid Steppe Hot, Temperate Dry Winter Hot Summer, Arid Steppe Cold and Cold Dry Summer Warm Summer.
To track changes over time, the researchers divided the historical records into five overlapping 30-year periods, known as epochs. These were 1951–1980, 1961–1990, 1971–2000, 1981–2010 and 1991–2020.
The results reveal that different parts of the country are experiencing distinct shifts in their climate patterns.
The study found that dry climate conditions have expanded across Northwest India, extending from western Uttar Pradesh towards eastern Uttar Pradesh.
The area classified as hot semi-arid increased from approximately one quarter of the region during 1951–1980 to one-third during 1991–2020. In contrast, the temperate zone, characterised by moderate temperatures and distinct seasonal changes, shrank from approximately one quarter to less than one fifth of the region.
Overall, around 7% of the region shifted towards a drier climate zone, alongside rising temperatures and declining rainfall.
Northeast India has also experienced a shift in its climate zones. The study found a transition from Tropical Savannah towards a temperate climate, with the temperate zone expanding during each successive period analysed.
Tropical Savannah climates are generally warm throughout the year and have a prolonged dry season. Temperate climates, as described in the study, experience hot summers and mild, dry winters.
These findings come amid concerns about rainfall variability across eastern and northeastern India. During the monsoon season referred to in the study, the region recorded the country's largest regional rainfall deficit. The researchers also identified a longer-term decline in annual rainfall over Gangetic West Bengal and Bihar between 1981 and 2020.
Unlike the more pronounced shifts observed in Northeast India, Central India recorded a relatively small expansion of the tropical monsoon climate zone.
Its area increased by around 2% between 1951–1980 and 1991–2020. This suggests a modest strengthening of monsoon-dominated conditions across parts of the region.
While some parts of the country are becoming drier, the study also identified areas where dry conditions have eased.
Western Saurashtra and Kutch, traditionally among India's driest regions, have shifted from an arid to a semi-arid climate between 1951–1980 and 1991–2020.
This change indicates that these areas have become less dry over time. The findings point to differences in how climate zones are shifting even within regions that have historically experienced water scarcity.
The study found a substantial reduction in the hot semi-arid zone across Peninsular India. Its share of the region declined from approximately 30% to 16% between 1951–1980 and 1991–2020.
Much of the land shifted towards tropical savannah conditions, which came to cover almost three-quarters of the region. The researchers associated this change with an increase in rainfall and wetter conditions. However, this trend does not extend across the entire peninsula. West Vidarbha and Marathwada in Maharashtra have gradually shifted towards the hot semi-arid zone. In contrast, the tropical monsoon zone has expanded along the Konkan coast, coastal Karnataka and Kerala. These contrasting patterns show why regional differences matter when assessing the effects of changing rainfall.
The researchers attribute the changes partly to the increasing influence of the negative phase of the Victoria Mode. This is a recurring pattern of sea surface temperature variations in the North Pacific Ocean that plays an important role in influencing rainfall variability. According to the study, this pattern contributes to the expansion of drier climate conditions over northern India.
The findings highlight the relationship between large-scale ocean temperature patterns and rainfall over different parts of the country. Understanding these connections is important when examining how climate conditions may continue to change.
The shift towards drier conditions in northern India is a particular concern because the region is one of the country's important agricultural areas.
The study's authors warn that these changes could affect agriculture, particularly paddy cultivation in northern India, by disrupting sowing and harvesting schedules. Changes in temperature and rainfall can also create challenges for water resources, food security and livelihoods.
The findings point to the need for long-term planning that accounts for regional differences in climate patterns. The exception of Vidarbha and Marathwada within the generally wetter Peninsular region, for instance, shows why broad regional averages may not capture local conditions.
India's changing rainfall patterns are not simply a shift between wet and dry seasons. They reflect wider changes in the climate zones that shape agriculture, ecosystems and access to water. The IMD study provides a historical picture of these shifts across seven decades and highlights the importance of taking large-scale ocean temperature patterns into account when planning for climate resilience.