Sweat just sits on your skin when humidity is high
As India enters an El Niño year in 2026, the country faces not merely a hot summer but a convergence of atmospheric forces that will widen the gap between what thermometers record and what human bodies endure. The weakening of monsoon winds, the suppression of oceanic cooling cycles, and the invisible weight of humidity together compose a climate vocabulary that is no longer abstract — it is physiological and, for many, existential. Those who labor under open skies, or carry the burden of chronic illness, will feel the full weight of systems that began their disruption thousands of kilometers away, over a warming Pacific Ocean.
- A 61% probability of El Niño persisting through year-end means India's monsoon is likely to arrive weakened, leaving agricultural regions parched and heatwaves more frequent and severe.
- The danger is not just heat but humidity — when wet bulb temperatures exceed 35°C, the body's sweat can no longer cool it, turning a physiological defense mechanism into a failing one.
- Outdoor laborers and people with heart disease or diabetes face the sharpest exposure, as the gap between a thermometer reading and actual bodily stress can be five degrees or more.
- Delhi's dry 40°C and Kerala's humid 40°C are meteorologically identical but experientially worlds apart — understanding that difference is now a matter of public health, not just weather literacy.
- Authorities and forecasters are working to translate complex climate indices — ENSO cycles, wet bulb thresholds, heatwave declarations — into warnings that reach people before the heat does.
India is entering an El Niño year, and the forecast is already being written in the language of disruption: weaker monsoons, delayed rains over farming regions, and heat that will feel far worse than any thermometer can convey.
To understand the season ahead, it helps to know the systems shaping it. The Western Disturbance — a fast-moving river of air embedded in the subtropical jet stream — governs winter and early spring weather across northwestern India and neighboring countries, bringing rain and snow to regions that depend on it. But summer belongs to a different force entirely.
El Niño is part of ENSO, a climate oscillation that cycles every two to seven years. Normally, prevailing winds push warm Pacific water westward, while cooler water rises along South America's coast. During El Niño, that balance breaks — surface waters warm abnormally, wind patterns shift, and the moisture that would otherwise feed India's monsoon is diminished. The US Climate Prediction Center puts the probability of El Niño conditions persisting from May through July at 61%, with expectations it will linger through year's end. The inverse — La Niña — typically strengthens India's monsoon, though in extremes it has also brought flooding.
The Indian Meteorological Department defines a heatwave when temperatures rise 4.5 to 6.4 degrees above normal, or when plains regions hit 45°C. But the thermometer tells only part of the story. Humidity is the hidden variable, and wet bulb temperature is its measure — the point at which sweat can no longer evaporate and the body loses its primary means of cooling. The IPCC warns that sustained exposure above 35°C wet bulb can be fatal; above 31°C, it becomes dangerous for anyone doing physical work outdoors.
This is why a 40°C day in Delhi — dry, swept by hot westerly winds — feels very different from the same temperature in Palakkad, Kerala, where humidity sits between 60 and 70 percent and perspiration offers little relief. The 'feels like' temperature captures this combined burden of heat, humidity, and wind. It is not identical to wet bulb temperature, but it is closer to how heat actually harms. The year ahead will test the distance between what the numbers say and what the body can bear.
India is entering what meteorologists call an El Niño year, and the implications are already written into the forecast: weaker monsoons, delayed rains across agricultural heartland, and heat that will feel worse than any thermometer can measure. To understand what's coming, you need to know the language of the systems that shape it.
Start with the Western Disturbance—a term you'll hear through winter and into early spring. It's a river of fast-moving air embedded in the subtropical jet stream, a high-altitude current that flows west to east across the Himalayan and Tibetan highlands. These disturbances are most active from December through March, steering weather patterns across northwestern India, Pakistan, Afghanistan, and Tajikistan. They bring rain and snow to regions that depend on it. But they're not the story of this summer.
El Niño is. The phenomenon is part of a larger climate oscillation called ENSO—the El Niño Southern Oscillation—which cycles through warm, cool, and neutral phases every two to seven years. The mechanism is oceanic. Normally, prevailing winds push warm surface water westward across the Pacific, toward Indonesia and the Philippines, while cooler water wells up from below along South America's northwestern coast. During El Niño, those surface waters warm abnormally, disrupting the wind patterns that carry moisture into India. The result is predictable and severe: monsoons weaken, agricultural regions dry out, and heatwaves intensify. The US Climate Prediction Center calculated a 61 percent probability of El Niño conditions persisting from May through July, with expectations it will linger through year's end. When the opposite occurs—La Niña, the cool phase—India typically receives stronger, moisture-laden winds and a robust monsoon, though in extreme cases that abundance has triggered flooding and crop destruction.
What makes this year's heat different from simple temperature is how it will feel on the ground. The Indian Meteorological Department defines a heatwave by two measures: either when temperatures depart 4.5 to 6.4 degrees Celsius above normal, or when the actual maximum reaches 45 degrees Celsius in plains regions (30 degrees in hills). A severe heatwave crosses 47 degrees. These thresholds must be met at two stations within a meteorological subdivision for two consecutive days before an official declaration. But the thermometer tells only part of the story.
Humidity is the hidden variable. Wet bulb temperature measures the lowest temperature your body can theoretically cool itself to through evaporation—essentially, the maximum temperature at which your sweat can still work. As humidity rises, sweat stops evaporating efficiently, and your body loses its primary cooling mechanism. The Intergovernmental Panel on Climate Change warns that sustained exposure to wet bulb temperatures above 35 degrees Celsius can be fatal, while temperatures above 31 degrees become dangerous for anyone doing intense physical work. Laborers, outdoor workers, and people with pre-existing heart disease or diabetes face the sharpest risk. The difference between dry bulb temperature (what a standard thermometer reads) and wet bulb temperature widens as air becomes drier—which is why a 40-degree day in Delhi, with its low humidity and hot westerly winds, feels manageable compared to the same temperature in Palakkad, Kerala, where humidity hovers between 60 and 70 percent and the air feels almost solid. In Palakkad, that same 40 degrees can feel closer to 45, turning perspiration into a losing battle.
This is what "feels like" temperature captures—the combined effect of heat, humidity, and wind on how your body actually experiences the environment. It's not the same as wet bulb temperature, but it's closer to how heat kills. A person checking the forecast sees 40 degrees and thinks they know what to expect. They don't. The year ahead will test that gap between what the numbers say and what the body endures.
Citas Notables
With increasing humidity, the sweat that humans generate to dispel heat does not evaporate, making it difficult for a person to regulate their body temperature— Explanation of physiological stress during extreme heat
A 40°C day in Delhi will not feel like a 40°C day in Palakkad, Kerala— Illustrating regional differences in heat perception
La Conversación del Hearth Otra perspectiva de la historia
Why does El Niño matter so much to India specifically? Couldn't the monsoon just be weak for other reasons?
El Niño disrupts the wind patterns that push moisture into India from the Pacific. When those winds weaken, the monsoon fails. It's not random—it's mechanical. And when the monsoon fails, agriculture fails, water reserves drop, and people turn to groundwater that may not be there.
So the heat and the dry conditions arrive together?
Exactly. El Niño doesn't just make it hotter. It makes it hotter while making it drier. The combination is what breaks systems—agricultural systems, water systems, human physiology.
You mentioned wet bulb temperature can be fatal above 35 degrees. How often does that actually happen in India?
The IPCC says sustained exposure to those levels is extremely unlikely to last more than a few hours. But "a few hours" is still dangerous for someone working outdoors, someone without air conditioning, someone whose body is already compromised.
And the difference between Delhi's heat and Kerala's heat—that's just humidity?
Humidity and wind. Delhi's dry heat lets sweat evaporate. Your body can cool itself. In Kerala, the air is already saturated. Sweat just sits on your skin. The same thermometer reading means something entirely different to your body.
So checking the forecast isn't enough?
Not even close. You need to know the humidity, the wind, your own health. The number on the screen is almost useless without context.