Pakistan’s rapidly expanding cities are becoming increasingly dangerous heat traps as concrete development, declining vegetation and limited shade intensify already extreme summer temperatures.

Researchers and public-health experts warn that the urban heat-island effect is increasing residents’ exposure to dangerous temperatures, particularly in densely built neighbourhoods with few trees, poor ventilation and large areas covered by asphalt or concrete.

Karachi appears to face one of the country’s most severe urban heat challenges. A 2026 multi-city study cited by climate researchers found that Karachi recorded an urban–rural temperature difference of approximately 4.5°C, the highest among the major Pakistani cities examined. The study also linked the loss of vegetation with rising land-surface temperatures.

What Is the Urban Heat-Island Effect?

The urban heat-island effect occurs when cities become significantly warmer than nearby rural or less-developed areas.

Roads, buildings, parking areas and concrete surfaces absorb heat during the day and release it slowly after sunset. This prevents many urban neighbourhoods from cooling properly at night.

At the same time, the removal of trees and natural soil reduces shade and evapotranspiration—the natural cooling process through which vegetation releases moisture into the atmosphere.

The result is a built environment that stores and amplifies heat.

Outdoor Workers Face Greater Exposure

People who work outside are among those facing the greatest risks.

Delivery riders, street vendors, traffic police, sanitation workers, construction labourers and rickshaw drivers may spend several hours in direct sunlight without reliable access to shade, drinking water or cooling facilities.

Previous microscale research in Karachi found that outdoor workers experienced temperatures around 5.5°C above the city’s recorded average when exposed to direct sunlight. Even shaded locations were approximately 1.8°C hotter than the broader city reading.

These differences matter because citywide weather-station readings may not reflect the actual temperatures experienced on crowded streets, beside traffic or near heat-retaining buildings.

Nights Are No Longer Providing Enough Relief

Hot nights can be particularly dangerous because the human body needs cooler temperatures to recover from daytime heat exposure.

When buildings and roads continue releasing stored heat after sunset, indoor temperatures may remain high throughout the night—especially in poorly ventilated homes without reliable electricity or cooling.

Repeated exposure without sufficient recovery can increase the risk of dehydration, heat exhaustion and potentially fatal heatstroke.

Older people, children, pregnant women, people with chronic illnesses and low-income households are often among the most vulnerable.

Urban heat is not only a weather problem. It is shaped by how neighbourhoods are planned, built, shaded and connected to essential public services.

Development Can Make Heat Worse

Unplanned urban growth can intensify the crisis when open land, wetlands and tree cover are replaced with dense construction.

Common factors include:

  • Loss of mature roadside trees
  • Large concrete and asphalt surfaces
  • Dark roofs that absorb solar radiation
  • Limited parks and public green spaces
  • Closely packed buildings that restrict airflow
  • Waste heat released by vehicles, generators and air conditioners
  • Insufficient shaded areas for pedestrians and public-transport users

These conditions can create localised heat hotspots where exposure is far greater than official city averages suggest.

Cities Need Heat-Resilient Planning

Reducing urban heat requires long-term changes in planning and public infrastructure.

Possible measures include:

  • Protecting existing mature trees
  • Expanding native urban vegetation
  • Creating shaded pedestrian routes and bus stops
  • Installing reflective or “cool” roofs
  • Preserving wetlands and open soil
  • Increasing access to public drinking water
  • Establishing cooling centres during extreme heat
  • Mapping neighbourhood-level heat hotspots
  • Adjusting working hours during severe heatwaves

Heat action plans should also identify communities with limited electricity, water, healthcare and green space.

A Growing Public-Health Emergency

Pakistan is already experiencing more frequent and intense periods of extreme heat. Cities that trap additional warmth can magnify those hazards and expose millions of residents to temperatures beyond what official forecasts alone may indicate.

Experts warn that without changes to urban design, tree protection and emergency planning, growing cities could face a public-health emergency in which extreme heat becomes an everyday feature of neighbourhood life.

The challenge is no longer simply how hot Pakistan’s cities become. It is whether those cities are being designed to keep people alive and safe as temperatures rise.