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Fair skies, foul balls: How weather influences baseball

A sign over center field at Truist Park announces that an August game in Atlanta between the Braves and the Washington Nationals had been postponed because of rain. (John Bazemore/AP)

On a late July evening at Dodger Stadium last season, baseball’s best player stood near the visitors’ on-deck circle, preparing to face one of baseball’s best teams. After Mike Trout watched a Los Angeles Angels teammate take a strike to open the game, far above the field, the press box loudspeaker announced, “7:11 start; 83 degrees at game time.”

Trout, a three-time American League MVP, is also a weather geek. And he will tell you that in baseball, temperature isn’t the only meteorological factor that matters. There was, for example, no mention of the humidity, the gentle wind blowing out toward center field, or cotton candy clouds in the orange sunset sky.

These details are more than just trivia amid the piles of data surrounding modern baseball. Unlike attendance, day of the week or choice of uniform, weather affects the game to a degree unique to any major American sport.

Affects everything

Because of Major League Baseball’s typically long season, weather delays or postponements can cause major headaches for players, team owners and those tasked with setting the schedule. They can also inconvenience fans, although the coronavirus has taken them out of the equation in 2020.

In baseball, weather’s influence is everywhere: A struck ball flies farther on a hot, humid day than on a cold, dry night; fielders lose balls in the sun and get fooled by the wind; and lengthy rain delays knock out pitchers.

In a normal season, undisturbed by a global pandemic, Major League Baseball and its teams must weigh the uncertainty of some forecasts against the potential impact on fans. For example, players might be able to play through a steady drizzle, but those in the stands might not want to sit through it. On the other hand, fans are understandably frustrated when a game is called and the weather turns out just fine.

Only eight MLB stadiums have roofs, all but one of them retractable. That means 22 stadiums must prepare for the chance of rain.

Bad weather in baseball is such a certainty, swaths of the official rule book are devoted to playing conditions and stoppages in play. Because of the pandemic this season, MLB altered one weather-related rule. In previous years, if weather caused the suspension of a game before it became official, it would start over from scratch. But in 2020, “all games cut short due to weather before becoming official will be resumed at a later date,” the rule book stipulates.

Rolling out the tarp

The weather was less than ideal when the Angels visited Baltimore in May 2019. More than two inches of rain fell upon Oriole Park at Camden Yards at the start of the three-game series, and daytime temperatures dropped 25 degrees from Friday to Sunday.

As could be expected, there were lengthy delays during the Angels’ only visit to Baltimore last season, and one game was played in a drizzle. Still, they got in the entire series, the Angels’ only scheduled visit to Baltimore in 2019, prompting the Angels to compliment the work of Orioles Head Groundskeeper Nicole Sherry and her crew.

Sherry’s prep for the Angels series had begun earlier in the week, while Baltimore was hosting the Boston Red Sox. Monitoring ominous forecasts, which are provided to the Orioles by a contractor, she knew an active few days were coming.

Neither MLB nor its teams lack for weather information. The commissioner’s office has forecasters on staff, and many clubs have multiple third-party weather services on speed dial. Stephen Lord, head groundskeeper at Cincinnati’s Great American Ball Park, said his club also has a corporate partnership with a local television station, with its weather desk providing an on-site meteorologist during games.

The Angels arrived in Baltimore on a Thursday, the night before the series began. The next day, Sherry pored over forecasts and weather radar so she could answer a simple question for team officials: Can we get this game in? It’s a big decision but one Sherry has made plenty of times before, including when the stakes are particularly high. Before Game 1 of the 2012 American League Division Series, she correctly predicted the Orioles’ first postseason game in 15 years could be played after a delayed start.

Groundskeeping "is not just raking dirt and mowing grass,” Sherry said. “It’s high, high stress levels at times.”

Calm before the storm

While Sherry is the on-field weather expert, she can’t halt or postpone a game herself.

The decision lies with the home team until managers exchange lineup cards. After that point, the umpire crew chief is in control. But MLB has the final word during the postseason.

Camden Yards has a “rain room” where Sherry can look at radar and weather reports. Umpires do not have access to live radar, but if weather threatens during a game, she takes a tablet out to the field, so the crew chief can see what’s going on.

“It’s just developing good communication with them, and a little bit of trust as well,” Sherry said.

In the Friday evening opener of the series in May 2019, Trout homered and doubled as Los Angeles jumped out to a big lead. Then, between the sixth and seventh innings, the weather disrupted the night. After crew chief Tom Hallion decided to clear the field, Sherry’s 30-person team jumped into action. As one group hustled to roll out the 28,900-square-foot tarp, others repaired the home plate area, pitcher’s mound and base paths before they were covered.

Had forecasts shown rain continuing through the evening, Hallion probably would have declared the game over right then and there. But on this night, forecasts showed precipitation coming down hard — with a risk of lightning as well — and then stopping.

Field of drains

As Camden Yards quickly became soaked by what one report called “a driving rain,” dropping 1.2 inches, the stadium’s drainage system was quietly at work siphoning away what fell on the grass. Sherry said it can drain 16 inches of water per hour through its sand rootzone, which means when the rain stops, water that’s collected on the tarp can be dumped in the outfield. Older parks don’t have this feature, with turf and dirt simply resting atop native soil.

There was a 109-minute delay before the game could continue. By the time that happened, only a couple hundred fans remained to see the final outs of an 8-3 Angels victory.

A few weeks later, a spritzing in California caused havoc, forcing the postponement of a May 22 game between the Angels and the Minnesota Twins.

The decision had Brad Ausmus, the Angels manager at the time, and Twins Manager Rocco Baldelli disagreeing whether the field was playable for the afternoon start, with the Angels skipper stomping on the waterlogged turf to emphasize the poor conditions. Then, when it came time for the teams’ player representatives and others, including Trout, to decide on a makeup date, they couldn’t see eye to eye on that, either.

The game was rescheduled for the next day. As Trout recalled months later, “Yeah, we played a long stretch.”

Good hitting, bad pitching or hot weather?

Baseball’s long-held conventional wisdom is that cold weather favors pitchers, and offense increases as the mercury rises. Now, thanks to analytics, precise numbers can be wrung from the data: “30 degrees of temperature is worth about 1.3 runs per game — split between both teams, of course. That means that a 100 degree day sees roughly 2.5 more runs than a 40 degree day,” wrote Jeff Long of Baseball Prospectus.

At the extremes, there is a 20-degree difference between the average game-time temperatures of the Bay Area stadiums versus the ballpark in Arlington, Tex. Like the mile-high altitude at Colorado’s Coors Field, it is a factor unaccounted for on back-of-the-baseball-card statistics, but a factor nonetheless.

Of course, there is a point at which hot weather becomes less a matter of sports than safety. During a Twins-Cubs game in June 2018, with Wrigley Field peaking at 96 degrees and a heat index of 107, there were 23 runs scored on 31 hits — as well as four players pulled due to heat-related illnesses.

Good pitching, bad hitting or cold weather?

On the other side of the thermometer, pitchers love the cold. They know hitters hate it — for one, the sting of hitting the ball off the bat’s handle seems magnified in chilly weather. But as long as the pitcher can feel his hands, game on.

Orel Hershiser, the former Dodgers ace who now provides color commentary for the team’s televised games, said he liked the weather to be as cold as possible when he pitched. Extremity-freezing weather was no big deal; under his cap, he’d have a hand warmer at the ready.

Hershiser had a dugout seat for one of baseball’s more notable cold-weather controversies. The third game of the 1988 National League Championship Series, between the Dodgers and the New York Mets, was held in terrible conditions, with a 43-degree temperature at first pitch and the Shea Stadium field described as “soaked.” Hershiser, the Dodgers starter, went seven innings before reliever Jay Howell entered to shut the door.

But in the eighth, Howell was ejected for having a foreign substance — pine tar ― in his glove. As Howell explained after the game, he needed something to help him grip the ball in wet, cold conditions, and the rosin bag wasn’t cutting it. With Howell tossed, the Dodgers bullpen imploded. The Mets won Game 3, though the Dodgers would take the series.

“They caught Jay,” Hershiser said, “but they should never have [ejected him] because they were forcing us to play in such bad weather.”

And why were they doing so? Because rain had postponed Game 3 from the previous night.

Know which way the wind blows

In the interface between weather and baseball, the variable with the widest range of consequences is the wind. Say every ballpark is experiencing a 10 mph breeze out of the south. What are the effects? Depends on how the stadium is constructed. Now reverse the wind’s direction, as frequently happens in Chicago. Then what?

“Wrigley, it’s either the smallest ballpark or the biggest,” Trout said.

Even when every park has the wind blowing out, no matter the compass direction, the impacts are diverse.

“A 10 mph wind blowing out is not equal in all parks,” said Kevin Roth, a meteorologist focusing on weather impacts in sports betting and fantasy sports for the site RotoGrinders. “In Wrigley, a wind blowing out at 10 mph or more increases home runs hit by 50 percent; in San Francisco, that same 10-plus mph wind increases home runs by just 6 percent.

“This is because Oracle Park was specifically designed to minimize the prevailing westerly winds in San Francisco, while Wrigley is an older park that didn’t give any thought to wind and has strong wind tunnels ripping through the ballpark.”

At Globe Life Park, the former home of the Texas Rangers, a wind coming in from left field would create a jet stream blowing out to right-center, Roth said. This lasted for many years, much to hitters’ delight, but was changed in 2015 when windscreens were built to block the flow.

Every ballpark has its own microclimate.

Sherry, the Orioles’ head groundskeeper, said Camden Yards, doesn’t get much airflow because it was built below street level and is surrounded by tall buildings. But at Great American Ball Park in Cincinnati, a prevailing southwest wind blowing in from the Ohio River cuts through the right-field foul pole, said Lord, the head groundskeeper. As a result, the air is calm in deep, straightaway right field, while the wind picks up in left field and center field.

Oftentimes at Wrigley, opposing players’ eyes light up when they see the flags pointing away from the plate. And that, said former Cubs outfielder Rick Monday, is when they get into trouble.

“Slumps, I believe, start as a result of bad habits,” said Monday, now a radio announcer for the Dodgers. “At Wrigley Field, I believe a lot of guys change their swings, and as a result, they got into slumps when they left.”

Blinded by the light

Dodger Stadium is not regarded as a place where the elements play much of a role — unless it’s cloudless with a bright sun. Then, daytime pop-ups and flyballs can be an adventure.

Problematic sun is an issue in almost every open-air ballpark where the fielders face the south and west. (As could be expected, the California stadiums, with their proximity to the coast, seem to have it the worst.) And that alignment is how MLB wants it. “It is desirable that the line from home base through the pitcher’s plate to second base shall run East-Northeast,” states Rule 2.01, which concerns how fields should be laid out. The aim is to keep the sun out of the batter’s eyes. But that means those in the field can suffer.

Monday has advice for those who find themselves under an unseen baseball plummeting earthward: “Use the bill of the cap, use your glove, step to the side if you can.

“Then prayer is last.”