A study in PLOS Climate reports that U.S. warming trends vary sharply by state and by whether researchers look at temperature averages or extremes. Using data from 1950 to 2021 for the 48 contiguous states, the authors found that 27 states showed statistically significant increases in average temperature, while 41 showed warming in at least one part of their temperature range—such as hotter highs in parts of the West and warmer cold-season lows in parts of the North.
Researchers María Dolores Gadea Rivas of the University of Zaragoza and Jesús Gonzalo of University Carlos III in Spain analyzed temperature records for the 48 contiguous U.S. states from 1950 to 2021, arguing that focusing only on average temperatures can obscure meaningful regional changes.
According to a PLOS summary of the work, the team used statewide average temperature data and more than 26,000 daily temperature readings per state to evaluate not only average changes but also shifts across the full range of temperatures experienced locally.
Their results point to a patchwork pattern. Only 27 states—about 55% of the contiguous U.S.—showed a statistically significant rise in average temperatures over the study period. By contrast, 41 states—about 84%—showed warming in at least one portion of the temperature distribution. The summary cites examples of different regional signatures, including higher annual temperature extremes along the West Coast and warmer minimum temperatures in many northern states.
The authors say these changes in extremes can matter for day-to-day impacts, including agriculture and public health, and may shape how communities perceive climate risks and design local responses.
In the study’s summary, the authors wrote: “Looking beyond average temperatures, we show that most U.S. states are warming in specific parts of the temperature distribution, even when average warming is not statistically significant. This reveals strong regional inequalities in how climate change is experienced across the United States.”
They also note that the same analytical approach could be applied to other climate indicators, including precipitation patterns and sea-level change.