Daily global average surface air temperature for 2024 (red), 2023 (orange), and all years between 1940 and 2022 (grey). Red shading indicates the difference between the daily global average temperatures from 2023 to 2024, for days where 2024 has been warmer than 2023. Data for 22 July 2024 is preliminary. Data source: ERA5, via Climate Pulse. Credit: C3S/ECMWF

Temperatures soared to unprecedented heights this past Sunday and Monday on what may be the hottest day scientists have ever recorded. Based on preliminary data from The Copernicus Climate Change Service (C3S), July 21, 2024, was the hottest global average daily temperature since at least 1940, by a small margin of 0.01ºC, at 17.09 degrees Celsius or 62.76 degrees Fahrenheit. The next day, Monday, July 22, 2024, beat the record again, at 17.15º C.

What was the previous record?

The previous highest daily global average temperature prior to this week was 17.08°C, a record set on July 6, 2023, as part of a long streak of record-breaking daily global average temperatures in July and August 2023.

What is the context of this record?

The top 10 daily global average temperatures have all occurred since 2015.

"What is truly staggering," C3S Director Carlo Buontempo said, "is how large the difference is between the temperature of the last 13 months and the previous temperature records. We are now in truly uncharted territory, and as the climate keeps warming, we are bound to see new records broken in future months and years."

What caused this new record?

Surface air temperature anomalies on 22 July 2024, relative to the average for the 1991– 2020 reference period. Data source: ERA5, via Climate Pulse. Preliminary data. Credit: C3S/ECMWF

The C3S reports that the global average temperature usually reaches a peak between late June and early August, coinciding with the peak of summer in the Northern Hemisphere. The larger landmasses of the Northern Hemisphere warm up faster than the oceans of the Southern Hemisphere cool down.

Their analysis indicates that the sudden rise in daily global average temperatures this month is related to well above-historical-average temperatures over Antarctica, which is continually breaking records for low ice extent since last year.

Climate scientist Zeke Hausfather told The Guardian the record was “certainly a worrying sign” on the back of 13 record-setting months adding, “It also makes it even more likely that 2024 will beat 2023 as the warmest year on record.”

The data comes as hundreds of cities in nearly every U.S. state – including parts of Alaska and Hawaii – are on track for one of their 10 warmest summers on record. About 100 cities are enduring their hottest start to summer on record. According to the European Union's Copernicus Climate Change Service, June 2024 was hotter than any June previously on record. Copernicus researchers found that temperatures worldwide each month for the past 12 months were 1.5 degrees Celsius greater than the average before the pre-industrial age.