RESEARCH
Heatwaves & Extreme Heat
Summer nights are no longer cooling down.
Key findings
- 01
Tripled since the 1980s
Heatwave days rose from about 5 to over 15 a year.
- 02
Nights warm fastest
Tropical nights grow twice as fast as hot days.
- 03
Humidity matters
Heat plus humidity raises risk more than heat alone.
Related papers
- 2026
Nighttime heatwaves are lengthening faster than daytime ones in East Asian cities
- 2026
열대야 지속 기간의 도시 규모 의존성
- 2025
Street trees and the timing of peak heat stress
- 2024
Compound heat and humidity extremes under 1.5 °C and 2 °C warming