The summer of 2026 has been relentless. Heat domes have parked over major American cities for days at a time, pushing temperatures past 100 degrees and shattering decade long records.

But while most people are focused on staying cool, something else is happening on the baseball diamond. Heat dome conditions are changing the game — and we are breaking down the science behind it.

A summer of record heat

Heat domes have been one of the biggest stories of the 2026 baseball season, and few ballparks have been spared.

A heat dome forms when a high pressure system parks over a region and traps warm air beneath it like a lid on a pot. The longer it sits, the hotter it gets — with no relief in sight.

Since July, major cities from Houston and Dallas to Atlanta and Philadelphia have been shattering temperature records. Stadiums including Daikin Park, Globe Life Field, Truist Park, Citizens Bank Park and Coors Field have all seen games played under extreme heat conditions this year.

What happens to the ball

Hot air is thinner and less dense than cool air — meaning there is simply less resistance pushing back against a baseball in flight. When temperatures climb, that ball encounters less pushback and travels farther on the exact same hit. Think of it like running into a light breeze versus a strong headwind. 

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Humidity plays a role too. Humid air is actually less dense than dry air, so a muggy summer night at a stadium like Daikin Park in Houston can push the ball even farther than a dry heat day.

That pop fly in April? In a July heat dome, it has a real chance of clearing the fence.

The numbers back it up

Researchers studying more than 100,000 major league games found that higher temperatures substantially increase home runs. More than 500 extra home runs between 2010 and 2019 are directly tied to warming, and researchers project several hundred more per season as temperatures continue to rise. Each additional degree of warming could add roughly 95 more home runs per season to MLB. 

A bigger story for baseball 

With several weeks left in the 2026 MLB schedule and heat domes still forming across the country, keep an eye on night games in cities like Houston, Atlanta and Philadelphia where heat and humidity are at their peak. Those conditions where the air is thinnest and the baseballs travel the farthest make every deep hit one to watch.

As long as temperatures keep rising, the box score will keep feeling it.

From Wrigley Field in Chicago to Dodger Stadium in Los Angeles, the summer heat is reshaping the game from the inside out, and the 2026 MLB season is playing out right in the middle of it.

Faiza Mohammed is a meteorologist intern at weather.com. She studied geography and worked with the Weather Dawgs team at the University of Georgia. She also received her master's in Earth and Atmospheric Sciences from the Georgia Institute of Technology.