Too Hot to Handle? How Heat is Reshaping U.S. Population Shifts

Using nationwide data, study results reveal a subtle dynamic: rather than forcing people out, rising heat is slowing growth in certain areas by discouraging new residents from moving in.

As extreme heat intensifies across the United States, it's widely assumed that rising temperatures will push people to pack up and leave. But new research from Florida Atlantic University challenges that narrative, showing that heat alone isn't driving Americans away - at least not yet.

In fact, the study finds that while higher temperatures may make some places less attractive to newcomers, they are not triggering large-scale out-migration. Instead, population shifts are shaped far more by economic opportunity, housing affordability and local quality of life than by climate conditions alone.

Drawing on nationwide county-level or county equivalent data within contiguous U.S. states including IRS migration records from 2020 to 2022, U.S. Census data, and climate measures from NOAA (data source) and the CDC, researchers analyzed how temperature changes influence where people move. The results reveal a more subtle dynamic: rather than forcing people out, rising heat is slowing growth in certain areas by discouraging new residents from moving in.

Findings, published in Sustainability, show that temperature increases alone are not a primary driver of where people choose to live - at least in the short term. Instead, migration patterns are shaped more strongly by economic opportunity, housing affordability and local living conditions. Counties with strong job markets, lower housing costs, and desirable amenities continue to attract residents even as temperatures rise, while population decline in other areas is more closely linked to long-standing economic and demographic trends than to climate alone.

Overall, many U.S. counties continue to experience positive net migration at the county level. Rapidly growing regions - particularly in the Sun Belt, including Florida, Texas and Arizona - continue to attract large numbers of new residents despite being among the areas experiencing the greatest increases in temperature.

"As extreme temperature anomalies increase, we don't see more people leaving," said Yanmei Li, Ph.D., senior author and an associate professor in the Department of Urban and Regional Planning within FAU's Charles E. Schmidt College of Science. "Instead, fewer people are moving in - especially to unusually hot areas - slowing population growth. It's less about people being pushed out and more about places becoming less attractive. At the same time, consistently warm climates still draw people, highlighting a contrast between steady warmth and extreme heat."

The findings also highlight an important dimension of climate and mobility: immobility. Rather than prompting widespread relocation, gradual climate stress may leave many people in place - either because they adapt or because financial constraints limit their ability to move. This raises the possibility that "trapped populations" could become an increasingly important feature of climate vulnerability, particularly in lower-income communities.

The research also shows that temperature change is highly uneven across the country. Warming is most pronounced in the Southwest, Southeast and parts of the Northeast, while other regions, including portions of the Great Plains, have experienced slower warming or slight cooling. On average, U.S. counties saw temperatures rise about 1.9 F between 2017 and 2021 compared to the 1901-2000 baseline, with local variation ranging from slight cooling (-0.1 F) to increases exceeding 3.7 F.

Approximately 394 U.S. counties have experienced warming above 2.6 F, and about 121 counties now exceed 3 F, indicating that many regions are already experiencing pronounced temperature increases. The strongest warming is concentrated in several Colorado counties - including Mesa, Ouray, San Juan and Montrose - as well as Summit County, Ohio. While warming is widespread across the country, its intensity varies significantly by region.

To examine whether migration patterns change at higher levels of heat exposure, researchers used a spline analysis to test for potential "tipping points." The results show that migration patterns remain largely stable at low to moderate temperature increases. A possible shift begins to emerge around 2.6 to 2.7 F of warming, but even beyond this point, the overall effect on migration remains relatively small.

"The absence of strong effects today does not mean climate will remain a minor factor," said Diana Mitsova, Ph.D., co-author and chair of FAU's Department of Urban and Regional Planning. "Our findings suggest that stronger migration responses could emerge in the future, particularly as rising temperatures interact with extreme events, long-term exposure, or constraints such as housing availability and insurance markets. Potential 'tipping points' may still lie ahead."

The effects of temperature change also vary across communities. In higher-poverty counties, rising temperatures are associated with increased out-migration, suggesting that more vulnerable populations may be more likely to leave under climate stress. At the same time, temperature alone shows little influence on attracting new residents.

Housing dynamics further shape these patterns. High housing costs do not necessarily deter people from moving into desirable areas, while high vacancy rates are associated with lower mobility overall. Counties with larger shares of highly educated residents tend to experience higher out-migration but lower in-migration, indicating more selective movement patterns.

"This dynamic has important consequences for long-term planning, including infrastructure investment, housing demand, and regional economic stability," said Li. "It also underscores the need to address not only climate adaptation, but also the structural barriers - such as inequality and housing access - that shape how people respond to environmental change."

For policymakers, the findings suggest a more targeted and measured approach. Rather than anticipating immediate large-scale climate migration, priorities should focus on strengthening resilience in place. Key strategies include investing in heat-resilient housing, upgrading infrastructure, addressing rising energy costs, and supporting renters and low-income households who face the greatest risk.

"Our changing climate is beginning to shape migration in subtle, indirect ways, primarily by interacting with existing economic and social systems," said Li. "How those systems evolve - and how effectively policy addresses vulnerability - will play a key role in determining whether climate becomes a more powerful driver of population movement in the future.

-FAU-