This is a series of articles examining heatwaves from every angle, exploring their causes, consequences, and the science behind them. It includes eight parts:
- Introduction
- Heatwave patterns
- Impacts on human health
- Impacts on urban areas
- Extreme heat in 2024
- Are heatwaves linked to climate change?
- Adapting to more frequent periods of extreme heat
- Temperature, apparent temperature, and heat indices
According to the annual report by the European Union’s meteorological service Copernicus, 2024 was the warmest year on record. The average global temperature reached 15.10 °C, which is 0.72 °C higher than the 1991–2020 average and 0.12 °C higher than the previous record year, 2023. Compared to the pre-industrial period (1850–1900), 2024 was 1.60 °C warmer.
This marks the first time that the 1.5 °C global warming threshold has been exceeded.
The year 2024 was also the warmest on record across all continental regions except Antarctica and Australasia. Record-breaking temperatures were observed in large parts of the oceans, particularly in the North Atlantic, the Indian Ocean, and the western Pacific Ocean.
Record-high temperatures in 2024 led to an exceptionally frequent occurrence of strong heat stress, defined as a UTCI temperature above 32 °C. As much as 61% of the land surface experienced more days with strong heat stress than usual.
Extreme heat stress, where the apparent temperature exceeds 46 °C and the risk of heatstroke becomes significant, typically occurs only rarely outside subtropical regions. However, in 2024, an above-average number of such extremely hot days was recorded in parts of Australia, North Africa, the Middle East, and the western United States.
The highest temperature was recorded in Algeria, where the UTCI temperature reached 59.1 °C, the highest value observed that year.
The extent of areas affected by heat stress was above average for most of the year. The record day occurred on 10 July 2024, when 44% of the land surface experienced strong to extreme heat stress, the largest area ever recorded on a single day. A similar peak (43%) was reached in August 2023.
For comparison, the long-term average of the annual maximum for the period 1991–2020 is approximately 39%.
In addition to intense rainfall in parts of South-East Asia and South Africa, June 2024 also witnessed devastating heatwaves, some of which were accompanied by large-scale forest fires. One example is the heatwave over Greece, where maximum temperatures exceeding 38°C were recorded in many areas for several consecutive days. Multiple countries in south-east Europe and the Middle East were also impacted. Our anomaly maps for June highlight widespread negative precipitation anomalies and positive temperature anomalies.
According to the methodology of World Weather Attribution, between 15 May 2023 and 15 May 2024, 76 extreme heatwaves were recorded, affecting 90 different countries. These events exposed billions of people to risk, particularly in densely populated regions of South and East Asia, the Sahel, and South America. During this period, 6.3 billion people - approximately 78% of the global population - experienced at least 31 days of extreme heat, with temperatures exceeding the 90th percentile of the 1991–2020 long-term average.
In the following period, between 15 May 2024 and 15 May 2025, another 67 heatwaves were identified. These extreme events occurred in 232 different countries and territories across all inhabited continents.
Explore how our tools help you prepare for heatwaves: Urban Heat Maps offer hyper‑local temperature insights tailored to city planning and public health, climate+ provides long-term modelled and observed climate data for strategic adaptation, and point+ delivers precise, customisable weather forecasts for any location.
This article is based in part on original work provided by Jaroslava Sochorova (Windy.com), which has been adapted and edited by meteoblue.
