Data
Heatwave days per person, observed and attributable to climate change, world and by country
Heatwave days that people were exposed to on average each year, 2020–2024, in the world and in each of 220 countries and territories: as observed, as expected in a modelled climate without human-caused warming, and the difference attributable to climate change, from the Lancet Countdown (indicator 1.1.1). Estimates for small countries are more uncertain, as the producer notes; where a country had fewer heatwave days than its modelled counterfactual, the attributable value is negative.
Latest value
25.8days
World, and countries and territories as the producer draws them (UN territories), 2024. Version 2025 report.
Heatwave days per person, observed and attributable to climate change, world and by country (days per person)
Show as a table
| Period | Scenario | Value (days) | Status |
|---|---|---|---|
| 2020 | Observed | 16.1 | final |
| 2021 | Observed | 14.9 | final |
| 2022 | Observed | 12.3 | final |
| 2023 | Observed | 22.5 | final |
| 2024 | Observed | 30.8 | final |
| 2020 | Expected without human-caused climate change | 1.9 | final |
| 2021 | Expected without human-caused climate change | 2.3 | final |
| 2022 | Expected without human-caused climate change | 2.3 | final |
| 2023 | Expected without human-caused climate change | 3.8 | final |
| 2024 | Expected without human-caused climate change | 5.0 | final |
| 2020 | Attributable to climate change | 14.2 | final |
| 2021 | Attributable to climate change | 12.6 | final |
| 2022 | Attributable to climate change | 10.0 | final |
| 2023 | Attributable to climate change | 18.8 | final |
| 2024 | Attributable to climate change | 25.8 | final |
Where it comes from
- Producer
- Lancet Countdown on Health and Climate Change (led by University College London) · Lancet Countdown 2025: heat, wildfire smoke, drought, extreme rain and deaths from air pollution
- Version
- 2025 report
- Fetched
- 2026-10-04 (automatically), 205,138 bytes
- Fingerprint
- sha256 53a22362f5b35c8cf91aa9d6c9f8ce0e7c97ce36f198f0b793ad70437989f632ETag "32152-6425ae06a502f" · Last-Modified Thu, 30 Oct 2025 07:05:39 GMT
- Copies
- No Wayback copy recorded yet.Our copy of the exact file
- Cite the producer
- Romanello M, Walawender M, Hsu S-C, et al. The 2025 report of the Lancet Countdown on health and climate change. Lancet 2025; published online Oct 29. https://doi.org/10.1016/S0140-6736(25)01919-1.
What was done to it
Read the sheets '2025_Report _Data_Global' (the world) and '2025_Report_Data_Country' (220 countries and territories by ISO3 code) of the indicator 1.1.1 (attributable heatwave days) workbook of the Lancet Countdown 2025 report, 2020–2024: heatwave days observed, expected without climate change (Counterfactual) and attributable to climate change (Attributable_to_CC), published as in the workbook. The producer's country names, WHO regions and HDI levels are not published.
Code: pipeline/src/envdash/transforms/impacts/lancet_countdown.py · code sha256 fecaf0b937e79c60… · inputs 53a22362f5b3…
Mapped each ISO3 code to the site's entity of that code (pipeline/geo/entities.csv); every code is in it.
Code: pipeline/src/envdash/transforms/impacts/lancet_countdown.py · code sha256 fecaf0b937e79c60… · inputs 53a22362f5b3…
Checked that observed days equal expected days plus attributable days in every row, and that every country has a value for each year of the world sheet. A country with fewer heatwave days than its modelled counterfactual has a negative attributable value, published as it is.
Code: pipeline/src/envdash/transforms/impacts/lancet_countdown.py · code sha256 fecaf0b937e79c60… · inputs 53a22362f5b3…
What it covers
- Geography
- World, and countries and territories as the producer draws them (UN territories)
- Basis
- A heatwave is at least two consecutive days when both minimum and maximum temperature exceed the local 1986–2005 95th percentile. Observed days from ERA5; days expected without human-caused warming from 24 paired CMIP6 climate model simulations. Each country's value is its people's average.
- Unit
- days per person (days)