# IMD study finds India's climate zones shifting, ties north India's drying to the Pacific

URL: https://upsc.help/current-affairs/2026-10-25/imd-climate-zones-shift-victoria-mode/
Date: 25 October 2026 (2026-10-25)
Source: The Hindu, Page 12
UPSC papers: GS1, GS3
Publisher: upsc.help (Pratidin), free and open-source UPSC Civil Services current affairs. Not affiliated with UPSC. Every fact was checked against the source reports by a separate review before publishing.

**In one line:** Comparing 30-year climate normals since 1951, IMD and IITM scientists find north India drying and the west coast getting wetter, with a North Pacific pattern called the Victoria Mode helping dry the Gangetic plains.

A study by scientists of the India Meteorological Department (IMD) and the Indian Institute of Tropical Meteorology (IITM), Pune, published in MAUSAM, IMD's peer-reviewed journal, has redrawn India's climate map for successive 30-year periods from 1951-1980 to 1991-2020 using IMD observations. Climate zones are defined by temperature and rainfall. The study finds that northern regions have trended drier while parts of the south and the west coast have become wetter. In northwest India, the hot semi-arid steppe zone grew from 25.7% to 33.1% of the area between the first and the latest period, and its eastern edge moved from western to eastern Uttar Pradesh.

Other shifts are just as striking. West Vidarbha and Marathwada moved mostly from tropical savannah to semi-arid steppe, while western Saurashtra and Kutch moved from fully arid to semi-arid. In northeast India the tropical savannah zone shrank from about 18% to 12% of the region, and the temperate zone now covers more than four-fifths of it, which the authors link to rising maximum temperatures. Gangetic West Bengal has shifted from tropical savannah to temperate. On the west coast, tropical monsoon zones have expanded in Konkan and Goa, coastal Karnataka and Kerala.

The study names the Victoria Mode, a recurring pattern of warm and cool sea-surface temperature anomalies in the North Pacific that is distinct from the better-known Pacific Decadal Oscillation, as a key driver of drying over the Gangetic plains. In its negative phase it steers moisture away from the region and sets up high pressure over Bengal, suppressing rain. IITM's Rajib Chattopadhyay said rainfall over Gangetic West Bengal and Bihar had been declining for four decades, even before this year's El Niño-linked shortfall, when east and northeast India recorded a deficit of 25.6%. The authors warn of effects on paddy, water and food security, and suggest building ocean patterns such as the Victoria Mode into long-term farm planning.

## Prelims facts

- An IMD and IITM study in MAUSAM compared India's climate zones across 30-year periods from 1951-1980 to 1991-2020.
- Northwest India's hot semi-arid steppe zone expanded from 25.7% to 33.1% of the area; its eastern edge moved from western to eastern Uttar Pradesh.
- In northeast India, tropical savannah shrank from about 18% to 12%; Gangetic West Bengal shifted from tropical savannah to temperate.
- Tropical monsoon zones expanded along Konkan and Goa, coastal Karnataka and Kerala.
- The negative phase of the Victoria Mode, a North Pacific sea-surface temperature pattern distinct from the PDO, is linked to drying over the Gangetic plains.

## Quick recall

- **Which institutions authored the climate zone study reported in October 2026, and where was it published?** IMD and IITM Pune; published in MAUSAM, IMD's peer-reviewed journal.
- **Which 30-year periods did the study compare at its ends?** 1951-1980 and 1991-2020.
- **Change in northwest India's hot semi-arid steppe zone?** From 25.7% to 33.1% of the area.
- **Change in northeast India's tropical savannah zone?** From about 18% to 12% of the region.
- **Climate class Gangetic West Bengal shifted into?** Temperate, from tropical savannah.
- **What is the Victoria Mode?** A recurring pattern of warm and cool sea-surface temperature anomalies in the North Pacific, distinct from the PDO.
- **Where did tropical monsoon zones expand?** Konkan and Goa, coastal Karnataka, and Kerala.
- **East and northeast India's monsoon deficit in 2026?** 25.6% below normal, the largest regional shortfall.

## Prelims practice question

The 'Victoria Mode', recently linked by an IMD study to drying over the Gangetic plains, refers to:

(a) A pattern of sea-surface temperature anomalies in the North Pacific Ocean
(b) A cycle of temperature differences between the western and eastern Indian Ocean
(c) A pressure oscillation over the South Atlantic Ocean
(d) The seasonal movement of the Inter-Tropical Convergence Zone over Australia

Answer: (a) A pattern of sea-surface temperature anomalies in the North Pacific Ocean. The Victoria Mode is a recurring pattern of warm and cool sea-surface temperature anomalies in the North Pacific, distinct from the Pacific Decadal Oscillation. Option 2 describes the Indian Ocean Dipole.

## UPSC previous-year questions this connects to

- UPSC Mains 2015, GS1: How far do you agree that the behaviour of the Indian monsoon has been changing due to humanising landscape? Discuss. (https://upsc.help/pyq/q278-far-do-you-agree-behaviour-indian-monsoon/)
  How to use this story in the answer: Use the study to show that monsoon behaviour is changing measurably, while noting that ocean patterns like the Victoria Mode, not only land-use change, drive part of it.
- UPSC Mains 2014, GS1: Most of the unusual climatic happenings are explained as an outcome of the El-Nino effect. Do you agree? (https://upsc.help/pyq/q030-most-unusual-climatic-happenings-explained-outcome-el-nino/)
  How to use this story in the answer: Argue that El Niño explains many but not all unusual climatic events, citing the Victoria Mode-linked decline in Gangetic rainfall.
- UPSC Prelims 2017, Prelims: With reference to 'Indian Ocean Dipole (IOD)' sometimes mentioned in the news while forecasting Indian monsoon, which of the following statements is/are correct? 1. IOD phenomenon is characterised by a difference in sea surface temperature between tropical Western Indian Ocean and tropical Eastern Pacific Ocean. 2. An IOD phenomenon can influence an El Nino's impact on the monsoon. (a) 1 only (b) 2 only (c) Both 1 and 2 (d) Neither 1 nor 2 (https://upsc.help/pyq/q032-reference-indian-ocean-dipole-iod-sometimes-mentioned/)

## Mains practice question

India's climate zones are shifting, with the north drying and parts of the west coast getting wetter. Discuss the role of distant ocean patterns in these changes and their implications for agriculture. (150 words)

### Model answer

An IMD and IITM study in MAUSAM compared India's climate zones from 1951-1980 to 1991-2020 and found clear shifts.

## Observed shifts
- Northwest India: hot semi-arid steppe up from 25.7% to 33.1% of area; edge moved to eastern Uttar Pradesh.
- Marathwada and West Vidarbha: tropical savannah to semi-arid steppe.
- Northeast: tropical savannah down from about 18% to 12%; Gangetic West Bengal now temperate.
- West coast: tropical monsoon zones expanded.

## Role of ocean patterns
- Negative Victoria Mode (North Pacific) steers moisture away from the Gangetic plains and builds high pressure over Bengal.
- El Niño years add short-term deficits, such as east and northeast India's 25.6% shortfall in 2026.

## Implications for agriculture
- Paddy sowing and harvest windows, groundwater demand and drought risk change.
- Need to include ocean indices in long-range planning, shift crop choices and invest in irrigation efficiency.

Climate zones are moving faster than farm planning; forecasting must look beyond the Indian Ocean.

## The basics

## Why this matters
School geography teaches India's climate regions as if they were fixed. A new IMD and IITM study shows they are moving within a single lifetime. That matters for crops, water and disaster planning, and it connects Indian weather to oceans far beyond the Indian Ocean.

## How climates are classified
Climate zones are drawn from long-term averages of temperature and rainfall, usually over 30 years (a climate normal). The class names used in the study, such as tropical savannah, tropical monsoon, hot semi-arid steppe, arid and temperate, are names found in the widely used Koppen climate classification. Comparing one 30-year normal with another shows how zones shift.

## What moved

The west coast moved the other way: tropical monsoon zones expanded in Konkan and Goa, coastal Karnataka and Kerala.

## A driver from the Pacific
India's rain is usually explained with El Nino and the Indian monsoon and the Indian Ocean Dipole. This study adds the Victoria Mode, a North Pacific pattern. In its negative phase it steers moisture away from the Gangetic plains and creates high pressure over Bengal.

## Why it matters on the ground
The authors warn about paddy sowing and harvest timing, water resources and food security. Their advice is to bring ocean patterns like the Victoria Mode into long-term agricultural planning, rather than reacting only to each season's monsoon.

## Sources

- https://superkalam.com/current-affairs/25-10-2026/a-distant-pacific-pattern-may-be-drying-north-india-study-pg12-3ef7f4de-f5ce-4c22-9192-3eb04edbbae6
- https://eastmojo.com/national-news/2026/10/23/imd-study-finds-northeast-bengal-shifting-out-of-tropical-climate-zone/
- https://www.shankariasparliament.com/current-affairs/victoria-mode-and-climate-change-in-india
- https://plutusias.com/?p=288877