From Western Disturbance to El Niño: The climate terms you’re hearing this summer, explained

India is experiencing compounding climate extremes this summer, with a Western Disturbance bringing unseasonal rain to the north while an El Niño event threatens weaker monsoon rains and more intense heatwaves. Western Disturbances are east-moving wind systems originating near Afghanistan and Iran, carrying moisture from the Mediterranean, Black, Caspian, and Arabian Seas. These systems typically occur from December to March but are now affecting weather patterns earlier than usual. The El Niño Southern Oscillation (ENSO) is a climate cycle involving Pacific Ocean temperature shifts that alter global weather. El Niño, marked by unusually warm eastern Pacific waters, disrupts moisture-bearing winds, often delaying or weakening India’s monsoon. The U.S. Climate Prediction Center forecasts a 61% chance of El Niño developing between May and July, persisting through the year, which could exacerbate heatwaves and dry spells in key agricultural regions. Heatwaves are declared when temperatures exceed 40°C in plains or 30°C in hilly areas, or when readings surpass normal levels by 4.5°C–6.4°C. High humidity worsens the perceived temperature, making conditions more dangerous. The India Meteorological Department (IMD) monitors these thresholds to issue warnings. El Niño’s opposite, La Niña, strengthens monsoons by cooling Pacific waters, but excessive rains can also cause flooding. This summer, however, the El Niño phase poses higher risks of drought-like conditions and prolonged heat stress. Experts warn of compounded challenges for agriculture, water supplies, and public health due to these overlapping climate disruptions.