Mid-2023 seems destined to go down as a pivotal period in climate change history — a time when planet Earth seemed to go from a simmer to a full rolling boil in a matter of weeks. What's jumping out isn't a single heat wave, but a one-after-another series of global and regional heat records astounding in both scope and persistence.

Hottest single days globally on record. Drawing on multi-source analyses from NOAA of daily global temperature that extend back to 1979, the Climate Reanalyzer website shows that July 3, 2023, was the warmest single day on record — only to be toppled by July 4, tied on July 5, and broken again on July 6 (see Figure 1 below). The Copernicus Climate Change Project, part of the European Center for Medium-range Weather Forecasts, also pegged July 3 as a global record.