Analysis: Climate change is increasing dangerous nighttime temperatures across the globe

The analysis finds that human-caused climate change has significantly increased the frequency of dangerous nighttime temperatures globally, affecting billions of people. Using the Climate Shift Index, the report quantifies additional nights above 18°C, 20°C, and 25°C, noting that these temperatures disrupt sleep and increase risks of cardiovascular conditions and mortality. The most severe impacts are observed in tropical regions and urban areas due to heat island effects, with specific cities in India, Indonesia, and Africa experiencing an additional month or more of extreme nighttime heat.

• Human-caused climate change has led to a significant increase in dangerous nighttime temperatures, with 2.4 billion people experiencing an average of at least 2 additional weeks per year where nighttime temperatures exceeded 25°C. Over 1 billion people experienced at least 2 additional weeks per year of nights above 20°C and 18°C.
• High nighttime temperatures pose severe health risks by preventing the body from recovering from daytime heat, which can increase the relative mortality risk on hot nights by 50 percent compared to non-hot nights. Poor sleep quality resulting from these temperatures is linked to impaired immune function, cardiovascular outcomes, cancer risks, diabetes, and shorter life expectancy.
• Vulnerable populations, including infants, the elderly, and pregnant women, are disproportionately affected. In pregnant women, sleep disturbance from heat is linked to increased risks of preterm birth, maternal health problems, and postpartum depression. Lower-income populations are also more affected due to poor housing quality and limited access to air conditioning.
• Urban heat island effects exacerbate the impact of hot nights as global populations urbanize, with 57 percent of the world living in cities in 2022 and a projected 68 percent by 2050.
• Regional analysis shows Southern Europe experienced the greatest number of days with minimum temperatures above 18°C added by climate change, averaging just over 2 weeks per year. For the 25°C threshold, the greatest increases were seen in Northern and Western Africa, Southeastern and Western Asia, and the Caribbean.
• At the country level, Uganda and Zambia were most impacted regarding the 18°C threshold, each seeing an additional month of such nights. For the 25°C threshold, 30 to 45 additional days were observed in countries including Trinidad and Tobago, Singapore, Brunei, Gambia, Cambodia, Thailand, Senegal, Niger, Guinea-Bissau, and French Polynesia.
• City-specific data reveals extreme increases: Kathmandu, Nepal, saw 89 additional days above 18°C. For the 20°C threshold, Bujumbura, Burundi and Barinas, Venezuela experienced 85 and 90 additional nights respectively. Guwahati, India and Cilacap, Indonesia were most affected by the 25°C threshold, with 85 to 86 additional days on average.

APA

Young, M., Pershing, A., Tannenbaum, A., & Martin, M. (2024). Analysis: Climate change is increasing dangerous nighttime temperatures across the globe. Climate Central. https://assets.ctfassets.net/cxgxgstp8r5d/60miPwR5LjnZ7CiETSIJ1P/d5c1e21825b36403723e02c1662aeb10/Analysis__Climate_change_is_increasing_dangerous_nighttime_temperatures_across_the_globe.pdf

Chicago

Young, Michelle, Andrew Pershing, Arielle Tannenbaum, and Megan Martin. Analysis: Climate change is increasing dangerous nighttime temperatures across the globe. Climate Central, 2024. https://assets.ctfassets.net/cxgxgstp8r5d/60miPwR5LjnZ7CiETSIJ1P/d5c1e21825b36403723e02c1662aeb10/Analysis__Climate_change_is_increasing_dangerous_nighttime_temperatures_across_the_globe.pdf.

Wikipedia

{{cite report |last1=Young |first1=Michelle |last2=Pershing |first2=Andrew |last3=Tannenbaum |first3=Arielle |last4=Martin |first4=Megan |title=Analysis: Climate change is increasing dangerous nighttime temperatures across the globe |publisher=Climate Central |date=8 August 2024 |url=https://assets.ctfassets.net/cxgxgstp8r5d/60miPwR5LjnZ7CiETSIJ1P/d5c1e21825b36403723e02c1662aeb10/Analysis__Climate_change_is_increasing_dangerous_nighttime_temperatures_across_the_globe.pdf |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{young2024analysis, author = {Young, Michelle and Pershing, Andrew and Tannenbaum, Arielle and Martin, Megan}, title = {{Analysis: Climate change is increasing dangerous nighttime temperatures across the globe}}, institution = {Climate Central}, year = {2024}, month = aug, url = {https://assets.ctfassets.net/cxgxgstp8r5d/60miPwR5LjnZ7CiETSIJ1P/d5c1e21825b36403723e02c1662aeb10/Analysis__Climate_change_is_increasing_dangerous_nighttime_temperatures_across_the_globe.pdf}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }