A new study shows that warming in the United States does not happen the same way everywhere. Researchers from Spain examined temperature data from 1950 to 2021 for the lower 48 states. They found that each region experiences heat differently, so each area needs its own plan.
The scientists looked at more than 26,000 daily temperature readings for each state. This gave them a full picture of how hot and cold days changed over time, not just the average.
Only 27 states (about half) saw a rise in their overall average temperature. But 41 states (more than four‑fifths) experienced an increase in at least part of their temperature range. In some places the hottest days got hotter, while in others the coldest nights became milder. For example, states on the West Coast are seeing larger differences between the hottest and coldest days, whereas many northern states are feeling warmer nights.
These differences matter for many reasons. Warmer peaks can stress crops, and milder lows can affect how diseases spread. Local governments and health agencies need to think about these specific changes when they make climate policies.
The same method could be used to study other climate factors, such as changes in rainfall or rising sea levels, giving scientists more tools to understand the Earth’s future.