If you live in the South, get ready to spend fewer days outside

If you’ve noticed it’s warmer than usual this October, you’re not alone. Across the country, people are reporting higher than normal fall temperatures and not yet donning their jackets or sweaters like they have in the past. It’s one example of how climate change is affecting the way we experience seasons—and it won’t be the last.

Climate change is altering how many days we can comfortably spend outside, and when those days occur throughout the year. Researchers at the Massachusetts Institute of Technology have been working to quantify this change through a metric of “outdoor days,” reframing the impact of climate change into a more understandable lived experience.

Their first paper on this, published in March 2024, found that those in the global south will see significant losses when it comes to the number of outdoor days, while northern countries could actually see more outdoor days throughout the year. The researchers’ latest paper, published in the journal Geophysical Research Letters, focuses on what these changes mean for the United States. The trend is similar: If you live in the South—particularly the Southwest—expect fewer outdoor days in your future. If you live in the Northwest, you could actually be spending more time outdoors.

This already rings true for some, like those who know to avoid going to Florida in the peak summer months because of the heat and humidity. But in the future, as emissions rise and climate change worsens, “Summer really becomes a more harsh climate,” says Elfatih Eltahir, an MIT professor of civil and environmental engineering and coauthor of both studies. Across the country, outdoor days are also shifting away from summer and more toward the spring and winter.

The study defines an outdoor day as one that ranges from 10 to 25 degrees Celsius (50 to 77 degrees Fahrenheit). That’s the thermoneutral zone in which humans don’t really need to shiver or sweat. “These are relatively pleasant days where people could enjoy the outdoors, meaning they could go for walks, go cycling, go jogging. They could have a barbecue outside,” Eltahir says. At hotter temperatures, outdoor activities quickly become unpleasant, and outdoor labor becomes dangerous. Temperature changes also affect tourism opportunities; already, extreme heat is changing where (and when) people take vacations.

The study projects that by the last 30 years of this century, the Northwest U.S. could see a 14% increase in outdoor days, compared to the period from 1976 to 2005. The Southwest, though, faces a 23% loss of outdoor days on average. If you personally think “outdoor days” could stretch over a different temperature range, MIT has a tool that allows you to select your state, plug in your temperature limits (up to 95 degrees Fahrenheit), and see the change yourself. That tool shows graphs for both how the number of outdoor days changes overall, and how the changes are reflected across seasons.

For Eltahir, the concept of outdoor days was spurred in part by a survey in which a majority of Americans said that global warming will harm people in the U.S., but just a fraction of them agreed that “global warming will harm me, personally.” That touches on how abstract climate change can feel. “It’s an attempt for me to bring the issue of climate change home,” he says. “When someone tells you global temperatures are going to increase by 3 degrees, that’s one thing. If someone tells you that your outdoor days will be dropping by 20% or 30%, that’s another thing.”