Several parts of India are experiencing floods, flash floods, landslides and severe waterlogging even though the country has received less seasonal rainfall than normal. This apparent contradiction shows why total rainfall alone cannot explain monsoon disasters. The timing,
intensity and location of rain are often more important than the seasonal average.
The 2026 southwest monsoon has produced two very different realities. Some cities and river basins have faced intense downpours, overflowing drains, flooded roads and landslides. At the same time, many districts continue to report deficient rainfall, long dry intervals and concerns
about agriculture and water availability.
This has raised an important question: how can floods occur during
a rainfall-deficit monsoon?
The answer lies in the difference between the total amount of rain received over several weeks and the intensity of rain falling within a few hours. A region may receive less rain than normal during the entire season but still experience one or two exceptionally intense events capable of causing severe flooding.
Is India Really Experiencing a Rainfall Deficit in 2026?
Rainfall during the monsoon is measured against a long-period average. According to assessments based on India Meteorological Department data, India’s cumulative monsoon rainfall was approximately 16% below normal by 27 July 2026. More than half of the country’s districts were reported to be in the deficient or large-deficient category.
The national figure, however, hides enormous regional variation. A state can have deficient seasonal rainfall while one district receives an extreme cloudburst-like event. Even within the same district, one location may be flooded while another receives relatively little rain.
Measures accumulated rainfall over several weeks or months.
Measures how much rain falls within a short period, such as one hour.
Depends on drainage, soil, rivers, slopes, land use and previous rainfall.
How Can Floods Occur When Total Rainfall Is Below Normal?
1. Rain Is Falling in Short, Intense Bursts
A rainfall deficit is calculated over a period such as a week, month or monsoon season. It does not describe how rainfall is distributed within that period.
Consider two hypothetical situations. In the first, 200 millimetres of rain falls gradually over twenty days. In the second, only 150 millimetres falls during the month, but 100 millimetres arrives within three hours.
The second month has less total rainfall, yet the flood risk may be much greater because water reaches the ground faster than it can infiltrate, drain or flow away safely.
This concentration of rainfall into fewer wet days is one of the main reasons why a deficient monsoon can still produce damaging floods.
2. Rainfall Deficit Is an Average, Not a Local Description
National and state rainfall departures are averages calculated across large geographical areas. Such averages can conceal local extremes.
For example, one part of a state may experience several weeks of weak rainfall while another district receives an exceptionally intense storm. When the two areas are combined, the state may still remain below its normal seasonal rainfall.
This is why national rainfall statistics should not be interpreted as a direct measure of local flood safety.
3. Urban Surfaces Prevent Water From Entering the Soil
Cities contain large areas covered by roads, rooftops, parking spaces, concrete and paving. These impermeable surfaces prevent rainfall from soaking into the ground.
Instead, water rapidly flows towards roads, drains and low-lying areas. When rainfall intensity exceeds drainage capacity, water accumulates within minutes. Encroachment on wetlands, lakes, floodplains and natural drainage channels makes this problem more severe.
Urban flooding is therefore not determined only by the amount of rain. It also reflects how a city has been planned and whether natural water pathways have been preserved.
4. Drains May Be Blocked or Too Small
Many drainage systems were designed using older rainfall patterns, smaller urban populations and lower levels of construction. They may not be able to carry the runoff generated by present-day extreme rainfall.
Plastic waste, construction debris, silt and illegal structures can further reduce the capacity of stormwater drains. Even a relatively localised rainstorm can then produce serious waterlogging.
5. Dry or Compacted Soil May Absorb Water Slowly
It is often assumed that dry ground will absorb rainfall easily. This is not always true. Prolonged dry conditions can harden or compact the soil, particularly where vegetation cover is limited.
When intense rain suddenly arrives, the upper surface may not absorb water quickly enough. A larger proportion becomes surface runoff, increasing the possibility of flash flooding and soil erosion.
6. Saturated Catchments Can Respond Rapidly
The opposite condition can also increase flood risk. If a river catchment has already received considerable rain, the soil may become saturated. Additional rainfall then flows directly into streams and rivers because little storage capacity remains in the soil.
River flooding can therefore result from cumulative rainfall over an upstream catchment, even when the location experiencing the flood has not received exceptionally heavy local rain.
7. Mountainous Regions Convert Rain Into Fast Runoff
In Himalayan and Western Ghats regions, steep slopes allow water to move quickly downhill. Intense rainfall can rapidly increase the discharge of small streams and seasonal channels.
Deforestation, slope cutting, road construction, unstable debris and unplanned buildings can increase the likelihood of landslides, debris flows and flash floods.
What Is the Difference Between a Flood, Flash Flood and Waterlogging?
| Event | Main characteristic | Common causes |
|---|---|---|
| River flood | A river exceeds its channel capacity and inundates surrounding land. | Prolonged catchment rainfall, upstream inflow, reservoir releases or saturated soil. |
| Flash flood | Water level rises very rapidly, often within minutes or hours. | Cloudburst-like rain, steep slopes, narrow valleys, dam failure or sudden release of blocked water. |
| Urban flooding | Streets, buildings and neighbourhoods are inundated within a city. | Intense rainfall, inadequate drains, concretisation, wetland loss and blocked water channels. |
| Waterlogging | Water remains temporarily accumulated because it cannot drain away. | Blocked drains, low-lying roads, poor gradients or inadequate stormwater infrastructure. |
Does Climate Change Explain the Contradiction?
Climate change does not create every individual flood or dry spell. Monsoon rainfall has always varied naturally from one year and region to another. However, a warmer atmosphere can hold more water vapour, creating conditions that may support heavier rainfall when storms develop.
At the same time, climate change can influence atmospheric circulation, ocean temperatures and the timing of monsoon systems. The result may be a more uneven rainfall pattern characterised by longer dry intervals and fewer but more intense rainfall events.
This means that a season can remain deficient in total rainfall while producing highly damaging extreme events. Climate risk must therefore be assessed using rainfall intensity, wet-day frequency, dry-spell duration and local exposure, not only the seasonal total.
What Role Do El Niño and Monsoon Systems Play?
The Indian monsoon is affected by several interacting systems, including the El Niño–Southern Oscillation, the Indian Ocean Dipole, the monsoon trough, Bay of Bengal depressions, western disturbances and the Madden–Julian Oscillation.
El Niño is generally associated with weaker monsoon rainfall over India, although its effect is not identical every year. Even during an El Niño-influenced or below-normal monsoon, low-pressure systems and depressions can generate episodes of very heavy rain along their path.
This is why seasonal rainfall forecasts should not be interpreted as forecasts of every extreme event. A below-normal seasonal outlook can coexist with local warnings for heavy or extremely heavy rainfall.
Why Are Indian Cities Particularly Vulnerable?
Rapid urbanisation has altered the natural movement of water in many Indian cities. Lakes have been reduced or disconnected, wetlands have been filled, streams have been narrowed and floodplains have been occupied.
At the same time, built-up surfaces generate more runoff. A storm that might once have been partly absorbed by soil, vegetation and wetlands can now send a much larger volume of water into a limited drainage network.
Major urban flood risks commonly include:
- construction over natural drainage channels;
- loss of wetlands and urban lakes;
- undersized or poorly maintained stormwater drains;
- mixing of sewage and stormwater networks;
- solid waste blocking culverts and drain openings;
- rapid construction in low-lying areas;
- limited open soil and vegetation; and
- weak coordination between land-use planning and flood management.
Can a Rainfall-Deficit Year Still Produce Water Scarcity?
Yes. Flooding does not automatically mean that sufficient water has been stored for future use.
Intense rainfall often runs rapidly into drains, rivers and the sea. It may not recharge groundwater efficiently, especially where the land is concretised or the rain falls faster than the soil can absorb it.
A city can therefore experience severe flooding during July and still face water shortages later in the year. Flood management and water conservation must be planned together rather than treated as separate problems.
What Should Cities Do?
Flood protection cannot rely entirely on constructing larger drains. Cities need a combination of engineered infrastructure, ecosystem restoration and better land-use planning.
- Protect and restore wetlands, lakes, river floodplains and natural
drainage channels. - Update drainage design standards using recent short-duration rainfall
intensity data. - Remove solid waste and silt before and during the monsoon.
- Map local depressions, blocked culverts and recurrent flood locations.
- Increase permeable pavements, parks, rain gardens and open soil.
- Restrict construction in floodplains and high-risk drainage zones.
- Develop neighbourhood-level rainfall and flood-warning systems.
- Improve reservoir-release communication with downstream communities.
- Combine rainwater harvesting with groundwater-recharge structures.
What Should People Do During Intense Rain?
- Follow official warnings from the India Meteorological Department,
district administration and disaster-management agencies. - Do not walk or drive through flowing floodwater.
- Avoid riverbanks, underpasses, culverts, steep slopes and seasonal
streams. - Do not shelter beneath unstable trees, retaining walls or damaged
structures. - Switch off electricity where water is entering a building, but only when
it is safe to reach the main supply. - Keep drinking water, medicines, identification documents, a torch and a
charged phone readily available. - Move vehicles and essential belongings away from known low-lying areas
before intense rainfall begins.
The Main Lesson From Monsoon 2026
The 2026 monsoon demonstrates why rainfall averages alone provide an incomplete picture of risk. India can experience a seasonal rainfall deficit and damaging floods at the same time because rainfall is not distributed evenly across space or time.
A few intense events can overwhelm urban drainage, destabilise slopes and cause rivers to rise rapidly, even when the accumulated seasonal rainfall remains below normal. Meanwhile, regions that experience floods may still face groundwater stress and water scarcity after the monsoon.
Future monsoon planning must therefore prepare for both extremes: too little rain over long periods and too much rain within a few hours.
Frequently Asked Questions
Can floods happen during a weak monsoon?
Yes. A weak or deficient monsoon refers to the accumulated seasonal rainfall. Localised extreme rain can still cause flash floods, river floods and urban waterlogging.
How can a district be rainfall-deficient and flooded?
The district may have received little rain during most of the season but experienced one exceptionally intense storm. Flooding depends strongly on rainfall intensity and local drainage conditions.
Does heavy rain remove the seasonal rainfall deficit?
Not necessarily. A short downpour may cause flooding but may still be insufficient to compensate for several weeks of below-normal rainfall.
Why does urban flooding happen so quickly?
Concrete surfaces generate rapid runoff, while blocked or undersized drains cannot remove water quickly enough. Loss of wetlands and natural channels further increases the risk.
Are rainfall deficits and drought the same?
No. A rainfall deficit is one indicator. Drought also depends on soil moisture, crop conditions, reservoir storage, groundwater and the duration and geographical extent of water shortage.
- India Meteorological Department:
Weather warnings, monsoon information and rainfall outlooks - IMD iRAINS:
District-wise and state-wise rainfall departure data - Down To Earth:
Floods, dry spells and rainfall deficit during the 2026 monsoon - National Disaster Management Authority:
Flood, landslide and disaster-safety guidance
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