Southwest Monsoon 2026: Mid-Season Assessment (End of July)

By the end of July, nearly half of India's southwest monsoon season (June–September) has been completed. This provides an opportunity to review the progress of the monsoon and understand what may happen during the remaining months (August–September).

1. Monsoon onset and advance

The southwest monsoon onset over Kerala occurred on 4 June 2026, about three days later than the normal onset date of 1 June. Following its onset, the monsoon advanced steadily across the country, with periods of rapid progress interspersed with temporary pauses. It eventually covered the entire country on 9 July 2026, about six days earlier than the normal date of 15 July.

It is important to note that the timing of monsoon onset or its rate of advance does not determine the seasonal rainfall over India. The seasonal rainfall depends on the evolution of large-scale climate drivers such as El Niño–Southern Oscillation (ENSO), the Indian Ocean Dipole (IOD), intraseasonal oscillations such as the Madden–Julian Oscillation (MJO), and the frequency of monsoon low-pressure systems and depressions during the season.

This distinction is well illustrated by the 2026 monsoon. Despite covering the entire country earlier than normal, the season accumulated a 13% rainfall deficit by the end of July, primarily because of the exceptionally dry June, although rainfall recovered substantially during July.


Figure 1: Progress of the Southwest monsoon in 2026. [Source: IMD]

2. Rainfall during June and July

The rainfall distribution during the first two months of the season has been highly uneven.

  • June 2026 was significantly dry, with 35% below-normal rainfall over the country as a whole.
  • July 2026 witnessed a marked recovery, receiving about 1% above-normal rainfall due to several active monsoon spells and the formation of low-pressure systems.
  • Despite this improvement, the cumulative rainfall during 1 June–31 July remained about 13% below normal (389.8 mm against a normal of 445.8 mm).

Figure 2: Monsoon Season (June-July) Rainfall Statistics. [Source: IMD]

 

Figure 3: Daily All-India Rainfall (mm) Variability from 1 June to 31 July 2026. [Source: IMD]

At the subdivision level, some areas experienced excess rainfall while others remained under significant rainfall deficit, illustrating the spatial variability that is characteristic of the Indian monsoon.

 

Figure 4: Observed Sub-divisional Rainfall Map during June and July (1 June to 31 July 2026). [Source: IMD]

4. IMD outlook for August–September 2026

According to the latest forecast issued by the India Meteorological Department (IMD), the second half of the southwest monsoon season (August–September) is likely to receive below-normal rainfall, with seasonal rainfall expected to be less than 94% of the Long Period Average (LPA). August 2026 is also likely to receive below-normal rainfall over the country as a whole.

The following is a forecast for the major climate drivers.

  • Moderate El Niño conditions are currently present over the equatorial Pacific and are expected to strengthen further during the remaining monsoon season.
  • The Indian Ocean Dipole (IOD) is presently neutral. Most forecasts indicate neutral conditions through much of the remaining season, although some international climate models suggest that a positive IOD may develop during September, which could partially offset the adverse influence of El Niño over some regions.

 

Figure 5: Rainfall Forecast for the Second half of the 2026 Monsoon season (August and September). [Source: IMD]

5. Summary

The 2026 southwest monsoon demonstrates an important feature of the Indian monsoon system: a slightly delayed onset and a rapid advance do not guarantee a good seasonal rainfall. The monsoon evolves continuously under the influence of large-scale climate drivers such as El Niño, regional weather systems, and intraseasonal variability. Although July substantially reduced the rainfall deficit created during June, the country as a whole remained below normal by the end of July. The latest IMD outlook suggests that rainfall during the remainder of the season is likely to remain below normal across the country as a whole. Therefore, careful monitoring of rainfall, water resources, agriculture, and weather forecasts during August and September remains important for planning and decision-making.

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