Status of Southwest Monsoon 2026 (June-August) and Outlook for September

The Southwest Monsoon 2026 commenced over Kerala on 4 June, slightly later than its normal onset date of 1 June. Thereafter, the monsoon advanced across the country and covered the entire country by 9 July.

a) Rainfall during June–August 2026

The country experienced a deficient June, followed by a near-normal July and another deficient August.

  • June: 106.8 mm against a normal of 165.3 mm — 35.4% below normal
  • July: 283.3 mm against a normal of 280.5 mm — 1.0% above normal
  • August: 213.5 mm against a normal of 254.9 mm — 16.3% below normal

Consequently, cumulative rainfall during 1 June–31 August 2026 was 603.7 mm, compared with the normal of 700.7 mm, giving an overall deficiency of 13.8%. Thus, despite a substantial recovery during July, the rainfall deficit accumulated during June could not be completely compensated, and rainfall again remained below normal during August.

Region  June 2026     July 2026      August 2026        Cumulative Jun–Aug
Northwest India-31.6%-4.0%-9.5%-10.7%
East & Northeast India-30.1%-29.0%-16.9%-25.7%
Central India-50.3%+33.0%-16.2%-3.8%
South Peninsular India-19.9%-25.0%-27.1%-24.2%
Country as a whole-35.4%+1.0%-16.3%-13.8%



Figure 1: Rainfall Statistics (1 June to 31 August 2026) for rainfall over India (Source: IMD)


The largest cumulative deficit has occurred over East & Northeast India and South Peninsular India, while Central India has remained relatively closer to normal. This regional variation is important from a climate-awareness perspective. "The monsoon was deficient" does not mean that every part of India received deficient rainfall. Some areas may experience excess rainfall even during a season that is deficient at the national scale.

Figure 2: Sub-division-wise rainfall anomaly from 1 June to 31 August 2026.

 b) What can we expect in September?

According to the latest IMD forecast, September 2026 rainfall over the country as a whole is most likely to be below normal, with rainfall expected to be less than 91% of the Long Period Average (LPA). Spatially, below-normal rainfall is likely over many parts of the country. However, rainfall is expected to be normal to above normal over some areas of Northwest India, Northeast India, East India, East central India and Southeast Peninsular India.

Therefore, September is not expected to provide a broad-based recovery of the accumulated rainfall deficit over the country. At the same time, the spatial pattern suggests that some regions may receive relatively good rainfall even while the country as a whole remains deficient.

 


Figure 3: Probability rainfall forecast for September 2026 [Source: IMD].

 

c) Climate factors influencing the outlook

One of the important large-scale climate signals associated with the present monsoon scenario is El Niño. Currently, strong El Niño conditions are prevailing over the equatorial Pacific Ocean, with sea-surface temperatures remaining above normal over the central and eastern equatorial Pacific. These conditions are expected to strengthen further in the coming months.

El Niño is an important climate driver because it can influence the large-scale atmospheric circulation and, in many years, is associated with weaker monsoon rainfall over India. However, it should not be interpreted as a deterministic relationship—El Niño does not mean that every region of India will necessarily experience deficient rainfall. Regional weather systems and other ocean-atmosphere interactions also play important roles.

Another important factor is the Indian Ocean Dipole (IOD). At present, IOD conditions are neutral. The Monsoon Mission Coupled Forecast System (MMCFS) indicates that neutral IOD conditions are likely to persist through September 2026. However, forecasts from some international climate centres suggest that positive IOD conditions may develop from September onward. The eventual evolution of the IOD could therefore influence rainfall patterns during the latter part of the monsoon season.

d) Climate Awareness

The 2026 monsoon provides a useful example for understanding the complexity of the Indian monsoon. The monsoon arrived over Kerala on 4 June and covered the entire country by 9 July, yet the country had accumulated a 13.8% rainfall deficit by the end of August. This demonstrates that: the date of monsoon onset tells us when the monsoon begins, but it does not tell us how much rain the country will receive during the entire season. For climate awareness, it is also important to distinguish between weather and climate. A few days of very heavy rainfall can produce flooding in a particular location, while the season as a whole can still be deficient. Similarly, a rainfall deficit at the national level does not imply drought everywhere.

e) Looking ahead

With September forecast to be below normal over the country as a whole, the accumulated seasonal rainfall deficit may persist or increase in several regions. Nevertheless, rainfall will continue to be spatially and temporally variable, and individual heavy-rainfall events can still occur. The 2026 season therefore offers a good opportunity to explain that monsoon rainfall is not simply about "more rain" or "less rain." What matters for society is also where the rain occurs, when it occurs, how intensely it falls, and how it is distributed through the season. In summary: By the end of August 2026, India had received 603.7 mm of rainfall against a normal of 700.7 mm (-13.8%). With September currently forecast to be below normal, the monsoon is likely to end with a significant spatial variation in rainfall, with some regions remaining deficient while others may experience normal or above-normal rainfall.

Comments

Post a Comment

Popular posts from this blog

A Possible El Niño in 2026: What It Could Mean for the Indian Monsoon

Image
Every year, the Indian monsoon is watched closely—not only by meteorologists, but by farmers, water managers, disaster agencies, businesses, and millions of ordinary citizens. The southwest monsoon provides nearly 70–80% of India’s annual rainfall (Figure 1) and supports agriculture, water resources, energy production, and livelihoods. This year, growing discussions around the possible development of an El Niño in the Pacific Ocean have raised an important question: Will El Niño affect India’s monsoon in 2026? Figure 1: Average monsoon season (June-September) rainfall (left panel) and Percentage of annual rainfall during monsoon season (right panel) The short answer is: possibly, but not always in a straightforward way. To understand what may happen, it is useful to look at the science behind El Niño, its historical relationship with the Indian monsoon, and why modern forecasting is more nuanced than simple cause-and-effect. What is El Niño? The El Niño–Southern Oscillation (ENSO) is...
Read more

El Niño, La Niña and the Indian Monsoon: A Climate Story from the Pacific Ocean to India

Image
Introduction Every few years, changes in ocean temperatures thousands of kilometers away in the tropical Pacific Ocean capture global attention. Terms such as El Niño , La Niña , and even Super El Niño begin appearing in weather and climate forecasts and news headlines. These phenomena are part of the El Niño–Southern Oscillation (ENSO), one of the most important drivers of year-to-year climate variability on Earth. But what do these terms mean, and how can changes in the distant Pacific Ocean influence the Indian monsoon? The answers lie in a fascinating scientific story that connects the Pacific Ocean, the Indian monsoon, and the pioneering work of Sir Gilbert Walker, who sought to unlock the secrets of monsoon prediction while serving in India more than a century ago. What are El Niño and La Niña? El Niño and La Niña are opposite phases of the El Niño–Southern Oscillation (ENSO), a naturally occurring ocean-atmosphere phenomenon in the tropical Pacific Ocean. El Niño El Niño occurs...
Read more

What Does IMD's Probabilistic Monsoon Forecast Really Mean?

Image
Introduction Every year, when the India Meteorological Department (IMD) releases its seasonal monsoon forecast, one common question immediately follows: “So, will the monsoon definitely be good or bad this year?” This year, many students, friends, weather enthusiasts, and members of the public asked similar questions after seeing IMD’s probabilistic monsoon forecast map. At first glance, the map may look confusing because it uses probabilities instead of giving a simple “yes” or “no” answer. However, this probabilistic approach is one of the most scientifically meaningful ways to describe seasonal monsoon forecasts. Unlike a daily weather forecast, which predicts conditions over the next few days, a seasonal monsoon forecast describes the likelihood of different rainfall outcomes several months in advance. Understanding this distinction is the key to interpreting the forecast correctly. Figure 1. Probabilistic forecast of rainfall categories (Below Normal, Normal, and Above Normal) o...
Read more