Why in News
Urban heat risk reflects regional heatwaves plus local amplification from built form, humidity, warm nights, occupational exposure and unequal access to cooling.
Static Foundation
Urban heat islands arise from heat-storing surfaces, reduced evapotranspiration, urban geometry and anthropogenic heat. Warm nights reduce recovery. Heat Action Plans combine forecasts, alerts, hospital preparedness, worker protections, water access and communication.
Prelims Focus
Urban heat island and meteorological heatwave are related but not identical. High humidity worsens heat stress by reducing evaporative cooling.
Mains Perspective
Cities need ward-level heat mapping, mortality surveillance, building-code reform, shaded mobility, cool roofs and enforceable worker protections. Tree programmes should measure canopy survival, not plantation counts alone.
Practice
MCQ: Surface materials and evapotranspiration influence UHI; humidity worsens heat stress; UHI does NOT require an official heatwave. Correct: 1 and 2.
Mains: Explain why Heat Action Plans must become climate-resilient urban planning.