India and Pakistan experienced unusually high temperatures from April into May, with reported daily highs well above 46 °C. An attribution analysis finds that anthropogenic has noticeably increased the likelihood, duration and intensity of such pre-monsoon heatwaves. As a result, hundreds of millions of people were exposed to for several days; health and economic burdens rose.
What defines the pre-monsoon phase
The pre-monsoon period between spring and the onset of the rains traditionally brings some of the hottest days of the year. Strong solar radiation, light winds and in parts of the region high humidity create a risky combination: hot days with little nighttime cooling. In densely populated areas where many people work outdoors or live in poorly ventilated homes, the strain is further increased.
Results of the attribution analysis
The research team used observational records, climate models and statistical methods to separate natural variability from human-driven trends. The result: pre-monsoon heatwaves occur more often today, last longer and are more intense than would be expected without . Crucial is not only the occurrence of single record temperatures but the extension of the hot period, which raises the cumulative burden on populations and .
Impacts on health, work and supplies
Medically, observed effects ranged from cramps and exhaustion to acute heatstroke and worsening of chronic conditions. Groups with limited protection are especially affected: street and agricultural laborers, construction workers and informal employees often cannot shift working hours. Older people, children and low-income households suffer further from inadequate cooling and limited access to medical care.
The economy also saw losses: workplace productivity fell due to heat-related shutdowns, crops and livestock suffered heat stress, and rising electricity demand for cooling strained grids and budgets. Local water shortages occurred as consumption and evaporation increased. In cities, the urban heat island effect amplified because sealed surfaces store release it slowly at night.
High vulnerability in densely populated regions
In the affected areas, very high population densities meet limited capacities: patchy air conditioning, informal settlements, precarious employment and sometimes weak public systems. These factors increase the risk of severe health outcomes and make service systems reach their limits more quickly—especially during multi-day heat events with little nighttime relief.
Immediate measures that help
Early-warning systems, heat action plans and adjusted working hours can reduce short-term risks. Cooling centers, public water points and targeted information campaigns have proven life-saving. Combined approaches are effective: reliable power for cooling, social safety nets for informal workers, mobile medical teams in hotspots and support for farms facing heat stress.
Long-term directions
Reducing emissions remains central to slowing further intensification. Without substantial cuts in CO2 and other greenhouse gases, pre-monsoon heat is likely to become more frequent, intense and prolonged. At the same time, adjustments are needed: more green and blue spaces, reflective surfaces, buildings with improved natural ventilation and resilient water-management systems.
The analysis makes clear: it is not only about peak temperatures but changed heat dynamics that simultaneously affect health, labor and infrastructure. A dual strategy is required—immediate protection against current extremes and long-term decisions for decarbonization and climate-resilient cities.