Monsoon 2026: Why Odisha Got Excess Rain When India Was Deficient — Bay of Bengal Low-Pressure Systems Explained

Odisha received excess rain in the 2026 southwest monsoon because a run of low-pressure systems from the Bay of Bengal kept crossing its coast, even as an El Niño year left India as a whole 12.6% short. Odisha ended the season 29% above its normal of 1,150.2 mm, the only one of India's 36 meteorological subdivisions with excess rainfall (IMD).

Why in news: IMD's season-end review shows the 2026 southwest monsoon closed at 87% of the long period average, the fourth-lowest since 2001, with Odisha the lone subdivision in the excess category. A deep depression late in the season then brought floods to north coastal Andhra Pradesh.

Updated (October 2026): season-end IMD figures replace the mid-season numbers; Odisha's rank, the system count, and a comparison table (monsoon depression vs cyclone) are new.

Key facts at a glance

Start with the headline numbers; the rest of this page explains why they point in opposite directions.

• All India: 759.4 mm against a long period average (LPA) of 868.6 mm → 87% of LPA, a 12.6% deficit; fourth-lowest since 2001 and 13th-lowest since 1901 (IMD).

• By region: Northwest 94.1%, Central 97%, South Peninsula 76%, East & Northeast 74% of LPA; East & Northeast India (1,017.1 mm) was the lowest since 1901.

• Subdivisions: 18 normal (53% of area), 17 deficient (42%), 1 excess: Odisha (5%).

• Odisha: 1,484.3 mm, 29% above normal and the fourth-highest since 1901 (record: 1,542.1 mm in 1961); Baleshwar was the wettest district at 1,907.1 mm.

Why was Odisha wet in a dry year?

An all-India deficit and an Odisha surplus can coexist because the two have different drivers: one is a large-scale circulation, the other a sequence of local weather systems.

• El Niño pulled the national total down: warm central and eastern Pacific → weaker monsoon circulation over India; IMD described El Niño as moderate and strengthening during the season.

• The Bay kept producing systems: ten systems affected Odisha, namely 2 deep depressions, 3 depressions, 2 well-marked low-pressure areas and 3 low-pressure areas (reports citing IMD data).

• The track decides who gets rain: monsoon lows form over the head of the Bay and move west-northwest along the monsoon trough, so Odisha's coast is often the first landfall.

• Result: about 1,058 mm of Odisha's 1,484 mm (roughly 71%) fell in about 42 days under these systems.

Analogy: think of the monsoon trough as a riverbed in the sky and each low as a boat floating down it. El Niño lowers the water level over the whole country, but the boats still pass the same landing, Odisha, and unload their cargo of rain there.

Worked example: Odisha normal 1,150.2 mm; actual 1,484.3 mm → excess = 334.1 mm → 334.1 ÷ 1,150.2 ≈ 29%.

How is a monsoon depression different from a cyclone, and how does IMD grade them?

The systems above differ in strength; IMD grades north Indian Ocean systems by maximum sustained wind speed, not by central pressure alone.

What was at stake: what did the late-season deep depression do?

The classification matters because rain, not wind, did the damage when a deep depression came ashore near Kalingapatnam, on the Odisha–Andhra border, in late September 2026.

• Strength: winds of about 55–65 km/h at landfall (media reports of IMD bulletins): a deep depression, never a named cyclone.

• Andhra Pradesh: heavy inflows swelled the Nagavali and Vamsadhara in Srikakulam district; hundreds of villages were flooded (media reports). Both rivers rise in southern Odisha, so Odisha's rain reaches Andhra downstream.

• Lesson: an unnamed system can flood more than a named cyclone; preparedness cannot wait for a name.

The wider stake is statistical: a national average hides extremes (South Peninsula 76%, Odisha 129%). That is the case for district-level forecasts and basin-wise flood warnings.

What UPSC asks

Both questions below test the drivers behind monsoon anomalies, the theme of this page.

UPSC CSE Prelims 2017, GS Paper I:
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.
Select the correct answer using the code given below:
(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2
Answer: (b) 2 only. IOD compares the western and south-eastern tropical Indian Ocean, not the Eastern Pacific. See the IOD and El Niño sections of the monsoon guide.

UPSC CSE Mains 2014, GS Paper I:
"Most of the unusual climatic happenings are explained as an outcome of the El-Nino effect. Do you agree?" (10 marks, 150 words)
Use 2026 as the example: El Niño explains the national deficit, not Odisha's excess.

See the detailed explanations: Prelims 2017 · Mains 2014 papers in the free PYQ vault, with year-wise analysis. Free to browse; free sign-up to download.

Mentor’s note

• Quote the season as a percentage of LPA, by region and subdivision. IMD frames it that way; the four regions are Northwest, Central, South Peninsula and East & Northeast India.

• Do not call Odisha's season the wettest ever. It was the fourth-highest since 1901, behind 1961, 2006 and 1956; rank claims need the full series.

• Prelims swaps 'depression' and 'deep depression'. Learn 31, 50, 62 and 89 km/h as boundaries.

• In GS1 and GS3 answers, split the season in two. El Niño and IOD set the all-India total; Bay systems set the regional split. Quote 87% of LPA, Odisha +29%, East & Northeast lowest since 1901.

Prelims traps and 60-second revision

Traps: (1) IMD grades by wind speed, not by pressure alone. (2) Deep depression is 50–61 km/h and is not named; naming begins at cyclonic storm. (3) IOD is a Western vs south-eastern Indian Ocean contrast, not Indian vs Pacific. (4) Odisha's 2026 total was the fourth-highest since 1901, not a record.

• Q: What was the all-India monsoon in 2026? 87% of LPA (759.4 mm), a 12.6% deficit.

• Q: Which subdivision got excess rain? Odisha, 29% above normal.

• Q: Which class is 50–61 km/h? Deep depression.

• Q: Which two drivers explain the split? El Niño (national deficit) and Bay of Bengal systems (Odisha).

• Q: Where do monsoon lows form and move? Head of the Bay; west-northwest along the monsoon trough.

Practice: Prelims MCQs

Q1. Consider the following statements regarding low-pressure systems over the north Indian Ocean:

1. A 'Deep Depression' has a higher maximum sustained wind speed than a 'Depression' but a lower one than a 'Cyclonic Storm'.

2. The India Meteorological Department classifies such systems solely on the basis of central atmospheric pressure.

3. A system is given a name only after it reaches the 'Cyclonic Storm' stage.

How many of the above statements are correct?
(a) Only one
(b) Only two
(c) All three
(d) None

Answer: (b) Only two
Explanation:
Statement 1 is correct: a deep depression is 50–61 km/h, between a depression (31–49) and a cyclonic storm (62–88).
Statement 2 is incorrect: IMD grades by maximum sustained wind speed.
Statement 3 is correct: naming begins at cyclonic storm (62 km/h or more).

Practice: Mains question

An all-India monsoon deficit can coexist with floods in individual States. Explain with reference to low-pressure systems over the Bay of Bengal. (Answer in 150 words; 10 Marks)

Terms to know

• LPA: long period average, the mean seasonal rainfall over a 50-year base period.

• Monsoon trough: the elongated low-pressure zone along which monsoon lows and depressions travel.

Frequently asked questions (FAQs)

How much rain did India get in the 2026 monsoon?

India received 759.4 mm against a long period average of 868.6 mm. That is 87% of normal, a 12.6% deficit and the fourth-lowest monsoon since 2001, according to IMD.

Why did Odisha get excess rain in 2026?

A series of Bay of Bengal low-pressure systems, including two deep depressions, crossed or skirted the coast, so Odisha ended 29% above normal despite El Niño. It was the only subdivision with excess rain.

What is a deep depression?

A deep depression is an IMD class of low-pressure system with maximum sustained winds of 50–61 km/h. It is stronger than a depression (31–49 km/h) but weaker than a named cyclonic storm (62–88 km/h).

Related reading

• Indian monsoon: mechanism, El Niño, IOD and the Northeast monsoon — UPSC notes

• Revise the NCERT basics of the Indian monsoon in NCERT Foundations

• Practise previous-year Geography questions in the free PYQ vault

• All Daily UPSC Briefs

Sources

• IMD — Salient features of the 2026 southwest monsoon season

• IMD RSMC New Delhi — tropical cyclone classification and naming

• UPSC — Civil Services (Preliminary) Examination 2017, General Studies Paper I

From The Daily UPSC Brief, 5 October 2026 — by Shivam Singh.