If you moved from the Snow Belt to the Sun Belt during the last few years, you might be part of a vanishing breed.

Since the widespread adoption of air conditioning in the 1970s, Americans have moved in droves from cold northern climes to sunny southern ones. That has led to booming populations in states such as Florida, Texas and Arizona, and a shift in economic activity from north to south.

But Sun Belt migration is now skidding to a halt, according to a new working paper from the Federal Reserve Bank of San Francisco. As climate change is making warm places hotter and cold places more livable, more Americas are staying put in the North, while others are leaving the South. In coming decades, net migration might flow in the other direction.

“The US population is starting to migrate away from areas increasingly exposed to extreme heat days toward historically colder areas, which are becoming more attractive as extreme cold days become increasingly rare,” economists Sylvain Leduc and Daniel Wilson wrote in the San Francisco Fed paper. “The previous century’s migration pattern from the Snow Belt to the Sun Belt is likely to ultimately be reversed.”

Leduc and Wilson analyzed temperate and population trends by decade, starting in the 1970s. They defined “extreme heat” as a day where the 24-hour average temperature was above 80 degrees, and “extreme cold” as a day when the average temp was below 20. Then they looked at population changes by county, excluding Alaska and Hawaii.

During the 1970s, “historically hot” counties had the strongest population growth. Historically hot counties also had the strongest net migration, or the difference between people moving in and those moving out, not counting births and deaths. Those numbers reflect the well-known trend of Americans leaving cold northern areas for the balmy South, especially once air conditioning provided relief from miserable heat.

During the next 40 years, from 1980 to 2020, the correlation between hot counties and net migration into those counties grew weaker, as the series of maps in the graphic below depicts. At the same time, the number of extreme heat days grew, and it grew faster in the hotter areas of the country. The number of extreme cold days declined, too. Overall, the South got hotter, while the chilly North got a little warmer.

By the last decade studied, 2010-2020, there was almost no correlation between extreme heat and migration, suggesting that warm temperatures are no longer a draw for people living in cooler places. The researchers also found that during that final decade, hotter countries in general saw declines in their higher-educated populations. Since higher-education people are wealthier, that suggests people with the financial means to do so are actually leaving warmer areas of the country.

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Southern states might still be gaining population, for reasons other than weather. Some have no state income taxes and friendly regulatory policies that draw businesses and workers. Elon Musk, for instance, recently said he’s relocating the headquarters for his companies Tesla (TSLA) and Space X from California to Texas. Labor unions are less entrenched in the south, which has drawn may foreign automakers and other types of manufacturers.

Yet the burden of climate change is becoming ever more tangible in the places most exposed to it—and the flight to safer ground might just be getting started. Scientists have been tracking signs of global warming for decades, but Americans as a whole are taking their time to recognize the risks it poses. In Pew Research polls, slightly more than half of all US adults view climate change as a major threat, up from 40% in 2010. The issue is also politicized, with just 23% of Republicans thinking climate change is a serious problem.

Climate deniers will find it increasingly difficult to explain away rising costs related to a warming planet. Home insurance rates are rising four times as fast in states with severe weather as in the rest of the country. Storm-prone states such as Florida and California are struggling to keep insurers from leaving the market, since they can refuse to write policies if regulators won’t let them raise premiums enough to cover the growing costs of dealing with disasters.

The number of costly storms has soared during the last 20 years, and hit a record in 2023, with 28 storms causing more than $1 billion in damage apiece. In 2021, the federal government revamped the national flood insurance program so it charges premiums more in line with risks and avoids billions in annual losses taxpayers had been funding. Houston, for instance, has become an "extreme weather magnet" that so far this year has already endured massive flooding from an early-season hurricane and a separate storm that blew out skyscraper windows.

As the cost of protecting a home against climate risk goes up, some property values are likely to go down. A 2023 study published in Nature estimates that residential properties in the United States are overvalued by as much as $237 billion because of flood risk alone, which implies that the value of affected properties could adjust downward by 10% to 12%. That could hit areas such as Appalachia and New England, where flood dangers have grown substantially, as well as coastal areas where climate risks are more familiar.

Fleeing climate risk in the United States doesn’t just mean a reversal of the longstanding north-to-south trend. “It’s important to understand that there’s no great location to move to,” says Bob Bunting, CEO of the Climate Adaptation Center and a former lead forecaster for the federal government. “Every region has its climate issues.” He cites repeat flooding in the midwest, likely driven by warmer air that can hold and unleash more water.

Still, changing migration patterns could leave fewer people exposed to the riskiest aspects of climate change. If north-south migration reverses and becomes south-north migration, it “could help mitigate the negative effects from hotter and more frequent extreme heat days, including from associated risks such as wildfires and drought, with fewer people directly exposed to them,” Leduc and Wilson write. Go north, young man.

Rick Newman is a senior columnist for Yahoo Finance. Follow him on X at @rickjnewman.

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