How weather affects baseball — and no one talks about it
- Ric Kearbey
- Jul 21
- 9 min read
Updated: Jul 26
Why heat, humidity, and wind should be the first thing you scout on game day
Whether you're a player wondering if you're in the starting lineup tonight or a fan checking who’s hitting cleanup for the Cubs–Cardinals showdown at Wrigley, the lineup is always worth a look before first pitch.
But some players are in the lineup every single game, and almost nobody checks them.
Heat. Humidity. Wind.
They’re on the field every inning, influencing everything from strikeouts to home runs. And honestly, they should probably be the first thing you look at.
Here’s why. You’re watching a summer baseball game. The sun’s relentless. The dugout feels like a convection oven. Your ace pitcher just lost command of his breaking ball.
Blame the weather.
No really. The atmosphere is out here throwing its own curveballs, and it impacts everything from velocity to how far that pop fly travels. Let’s break it down.
1. Humidity messes with your grip...and your distance
Ever try to hold onto a baseball when it feels like the air itself is sweating? That’s humidity in action. Moisture in the air makes it harder to grip the seams, especially for pitchers trying to spin a slider or bury a changeup.Even the rosin bag waves the white flag eventually.
But here’s where it gets nerdy, and surprising. Hot and humid air is actually lighter than cool and dry air. That sounds backwards, but it’s true. The water vapor in humid air replaces heavier oxygen and nitrogen molecules, making the air less dense. And less dense air means less drag on the ball.
This can be the difference between warning track power and a home run. And I’ve seen it firsthand.
During the great Mark McGwire and Sammy Sosa home run chase in 1998, I was doing the weather for ABC in St. Louis. On one unusually cool August night, McGwire crushed a deep fly to left-center in his third at-bat. The center fielder sprinted back until he ran out of room, which usually meant turning around to watch another Big Mac blast leave the park.
But this time, something weird happened. The high, majestic fly ball just…died. It dropped right into the glove of the center fielder, standing with his back against the wall.
Just hours earlier, on our 6 PM newscast, I had interviewed a physicist from Washington University in St. Louis to calculate how much less a baseball would travel in that night’s cool, dry air compared to the typical hot and humid conditions of a normal August game.
I aired the story from the field a little over an hour before first pitch. I wasn’t psychic, I was just nerding out on the weather. I had trained extensively in atmospheric physics. I was a big baseball fan. And I was always pitching stories to my news director that got me on the field with my favorite team.
I wasn’t trying to force a weather angle that night, but when you’ve got a Weather Nerdy soul, these ideas have a way of jumping out at you.
Game time temp: 62°F, Dew point: 55°F, Normal August: 85°F, dew point 72°F
We ran the numbers: a fly ball would travel about 9 feet less in the chilly, dry air. That’s the difference between a 400-foot shot and a 391-footer.
Busch Stadium center field was 402 feet deep.
That night, McGwire’s blast? 402 feet.
On a normal night, that ball would have landed in the third or fourth row...a souvenir and another step toward Roger Maris’s record. Instead, it was a long, loud out.
That night, the atmosphere robbed McGwire of a home run, and I knew exactly why.
2. Hot air is thin air, and it turns warning track outs into souvenirs
We already saw how cool, dry air can steal a home run. But the flip side? That’s where the magic happens.
Why hot weather boosts offense:
Hot air is lighter, reducing drag on the baseball
Humidity thins the air even more
Baseballs carry farther in warm, moist conditions
Backed by science:
A 2023 study of 100,000+ MLB games (1962–2019) found that every 1°C increase (1.8°F) led to a 1.96% rise in home runs per game
Since 2010, more than 500 home runs have been linked to hotter-than-average weather
Summer = long ball season:
Home run rates peak in July and August
The average distance of barreled fly balls (well-struck hits) jumps from 385.5 feet in April/May to 387.3 feet in June/July
That small boost? It’s the difference between a warning track out and a third-row souvenir
Ballpark examples:
Wrigley Field (Chicago): Warmer summers add 5–6 extra home runs per season. Thin air turns long flyouts into game-changers
Busch Stadium (St. Louis): During the 1998 home run race, hot, humid nights helped McGwire’s rockets clear the fences
Pitchers struggle in the heat too:
Thinner air weakens the Magnus effect, making curveballs break less and sliders flatter
Velocity drops as core temperature rises
Focus dips, movement flattens, and fatigue sets in quicker
Ever seen a starter cruise through four innings, then suddenly unravel in the fifth on a sweltering July day? That’s the heat rewriting the outcome.
So if your team’s cleanup hitter starts heating up in July, it’s not just the hitting coach.
Sometimes it’s the atmosphere doing the heavy lifting.
3. How wind changes the game — from Wrigley Field to your backyard
Wind is the invisible MVP (or villain) of baseball, depending on who you ask. And nowhere is that more true than at Wrigley Field, where the ballpark's open design and proximity to Lake Michigan turn every gust into a potential game-changer.
Wrigley Field: Where flags tell the story
Wrigley's history with wind is legendary. Some days, it feels like the outfield bleachers are a jet stream. Other days, the wind blows in like an invisible wall. And players, especially pitchers and power hitters, pay close attention.
• Wind blowing in: Home run suppression zone. A 10+ mph headwind can reduce home runs by 33%, turning potential game-tying blasts into warning track outs.
Example: In May 2023, Cody Bellinger, of the Cubs, hit a 107 mph fly ball in the 9th inning. In calm conditions, it's a home run. With a 17 mph wind blowing in? The ball lost 40 feet and the Cubs lost the game.• Wind blowing out: Welcome to the launch pad. Home runs increase by 50% when wind blows out at 10+ mph. Even weak contact can get carried into the seats.
Example: In a 2017 Pirates-Cubs game with 24 mph winds out to center, six home runs were hit. One was a 95.7 mph, 41-degree fly ball from Francisco Cervelli that had just a 6% chance of going out, but the wind gave it wings.• Crosswinds: The wildcard. At Wrigley and other stadiums like Citi Field, crosswinds can cause fly balls to drift 30 to 50 feet, messing with outfielders and pitchers alike. In a 2023 game, Patrick Wisdom hit a towering popup that drifted 50 feet sideways and dropped in for a double.
Pitchers: wind is a love-hate relationship
Wind doesn’t just impact hitters. Pitchers adjust their entire game plan based on the breeze.
• Wind blowing in: Most pitchers love it. It lets them pitch to contact and dare hitters to elevate. Fastball-heavy pitchers thrive. The outfield plays shallow. Everyone breathes easier...unless you’re the hitter.
• Wind blowing out: This is the nightmare. Even perfectly executed pitches can be punished. Groundball pitchers get the nod, but even then, a pop-up with help from Mother Nature can turn into a 2-run homer.
• Crosswinds: For pitchers who rely on spin, sliders, curveballs, cutters, crosswinds can wreak havoc. They might break too much, not enough, or drift right into the barrel. It’s the baseball version of Russian roulette.
Some pitcher perspectives:
• Jake Arrieta (2017): After giving up multiple wind-aided homers at Wrigley, he said, "Every mistake gets punished. You can't even miss a little."
• Zack Greinke (Royals): At wind-prone Kauffman Stadium, he studies wind flags like they're scouting reports. When the wind blows in, he goes after hitters more aggressively.
• Max Scherzer (Mets): Described Citi Field crosswinds as unpredictable. His slider either dances too much or not enough, changing his whole approach.
Wrigley isn’t alone
Other parks have wind personalities too:
• Oracle Park (San Francisco): The windiest MLB park in 2023. Swirling gusts can kill home runs or carry them into McCovey Cove. Outfielders get whiplash.
• Citi Field (New York): Led MLB with 28 wind-created home runs in 2023-24. Crosswinds pull balls down the left field line, boosting scoring unexpectedly.
• Kauffman Stadium (Kansas City): Most wind-prevented home runs in 2023-24 with 67. Outfielders play in, fly balls die, pitchers grin.
• Globe Life Park (Texas): Former home of the Rangers had a notorious right-center jet stream. Pop flies became bombs, frustrating pitchers on the regular.
Big picture: wind is the ultimate wild card
Pitchers study flags. Hitters curse the breeze. Outfielders hold their breath on every fly ball.
• When the wind blows out: Deep fly balls become home runs. Runners stretch singles into doubles. Defensive positioning shifts back.
• When the wind blows in: Fly balls hang and die. Outfielders play shallow. Pitchers get bold. Fans groan as balls fall short of the ivy.
Wind doesn’t just influence outcomes, it changes strategy. And no place teaches that better than Wrigley Field, where baseball and weather constantly square off.
So the next time you're watching a game and wondering why a ball carried, or didn’t, check the flags. The wind may be deciding the outcome before the pitcher even releases the ball.
4. How weather affects baseball performance when it’s brutally hot
When it comes to how weather affects baseball, extreme heat is one of the most brutal variables. Ever try to sprint in 95 degrees with full gear and zero shade? Players do, and it’s more than just uncomfortable. Heat crushes performance.
What happens in the heat:
Pitchers lose velocity
Focus fades
Muscles cramp
Catchers slow-cook behind the plate
By the sixth inning, heat fatigue can rewrite the outcome of the game as much as any scouting report.
Just ask Elly De La Cruz. In a 2025 scorcher in St. Louis, he vomited near second base in the fourth inning. He’d hydrated all day. Didn’t matter. He still launched a 2-run homer in the seventh, but not before the Cardinals' grounds crew had to mop up, and fans retreated to firetruck spray outside Busch Stadium. Even Cincinnati’s pitcher said it felt like "stepping into an oven."
In Chicago, that same day, it wasn’t much cooler:
Mariners reliever Trent Thornton collapsed from heat illness mid-inning
The umpire vomited in the dugout
A Cubs staffer needed medical help post-game
Fans clustered in fountains and shaded corners while misting stations ran full blast
In Atlanta, of called Hot-lanta because of intense summer heat, catchers are often told not to run, just to survive. Pitchers like Detroit’s Casey Mize cramp up mid-game, even after loading up on bananas and Gatorade.
Meanwhile, sweaty hands wreck pitch grip, drop velocity, and increase late-game errors. That’s not just anecdotal. Studies show higher temps reduce focus and increase mistakes across the board.
Other examples:
Denver: In 98-degree heat, outfielders feel like they’re chasing rockets
Tampa: Rays players called their outdoor 2025 stretch "preparation by fire"
And this isn’t rare anymore. As summers heat up, games in places like St. Louis, Atlanta, Chicago, and beyond are becoming endurance contests:
Managers shorten outings
Substitutions spike
Umpires sometimes need IVs
What teams are doing about it:
Hydration protocols with electrolyte-rich drinks and pre-game testing
Cooling tech like vests, ice towels, and CoolMitt devices between innings
Modified prep routines with shorter batting practice and shaded warmups
Medical staff monitoring players closely for heat stress symptoms
More night games to reduce exposure in scorching cities
Hot weather doesn’t just raise home run totals. It melts stamina, saps focus, and redefines strategy inning by inning.
And it’s not just MLB players adapting to the heat...
The wildly popular Savannah Bananas just wrapped up a sold-out weekend at Busch Stadium in sizzling St. Louis.
The heat index flirted with 110°, and somehow Jesse Cole, the ringmaster known as the “Yellow Tux Guy,” still pulled off his signature suit without melting into the outfield grass.
In case you're one of the three people left in America not familiar with Banana Ball...Think of it as baseball struck by lightning, fast, unpredictable, and occasionally interrupted by a synchronized dance break from the pitcher or a center fielder doing backflips while catching fly balls.
These wildly entertaining exhibition games are selling out MLB stadiums across the country. The Bananas even convinced three Cardinals legends Adam Wainwright, Lance Lynn and Jason Isringhausen to throw a few pitches in the madness.
If anyone deserves a hydration break and a standing ovation, it's the guy in full polyester sunshine while the turf cooks at triple digits.
And we haven’t even mentioned the other players, like rain, cold, and snow
They may not show up often, but when they do, they can completely change the game.
How weather throws a wrench in the action:
Rain slicks up baseballs and slows down infield hops
Cold air thickens the atmosphere, making it harder to hit for power
Snow has even fallen during games — yes, in April
Wet fields don’t just affect footing, they slow base runners and kill momentum on sharp grounders
A little-known secret: Over the years, there have been whispers about certain trickster grounds crews who shall go unnamed, giving the infield an extra soak before game time. Especially when the visiting team had a game-changing speedster leading off.
Call it strategy. Call it gamesmanship. Either way, it’s weather in action.
Bottom line: the weather isn’t background noise, it’s part of the game plan
It should be on the scouting sheet. On the pre-game radar. In the dugout conversation. Because whether it’s a fastball losing spin or a blooper that carries just enough, the weather is always in play.
Want more stories like this? Curious why curveballs break differently in Denver or how fog delays impact football more than rain?
That’s exactly what you’ll find at WeatherNerdy.com, your daily dose of weather curiosity.