The over/under total at sportsbooks for one of this weekend’s wild-card games dropped dramatically earlier this week. The reason? The weather.

Before the game was moved from Sunday to Monday, the Buffalo Bills, no strangers to frigid conditions, were set to host the Pittsburgh Steelers in 40 mph winds. Sports bettors and bookmakers took notice. The consensus opening odds for the total points scored fell rapidly from Sunday to Monday, with the over/under in the Bills game quickly falling from as high as 43 to as low as 35.5. (It was pulled off the board on Saturday and reopened at 38.5.)

“Once the news comes out that there’s horrible weather, [the under] just gets pounded relentlessly,” Adam Pullen, assistant director of trading for Caesars Sportsbook, said. “It’s going to be interesting to see where the bottom is. Where do the sharps start betting the over?”

At BetMGM, that number was 35.5, a full 6.5 points lower than the opening number. Christian Cipollini, trading manager for sportsbook BetMGM, said the forecast for Buffalo prompted a flurry of bets on the under from 7 a.m. to 11 a.m. ET on Monday. Cipollini said they moved the total quickly but still struggled to slow down the rush of bets on the under.

“Every time that we thought that we had gotten to a place where the action would end, it just kept going lower,” Cipollini told ESPN.

Kansas City is also expecting extreme weather for the Dolphins-Chiefs game Saturday, but that forecast didn’t have the same impact on the betting line.

“The wind is usually actually the bigger indicator of changes to what that total will be, more so than in that Chiefs game that also is going to have some weather,” Cipollini said.

Weather still could be a factor Monday, with forecasts predicting snow and windy conditions. The wind will make passing difficult and can affect the game by “forcing [the teams] to run the ball more, reducing the number of possessions, inaccuracies with kicking direction and loss of distance, and then slower reaction time by the defense,” said Ivetta Abramyan, a meteorologist, professor and one of three co-founders of Bettor Weather, a website that provides data on the impact of weather on games and betting lines.

Weather has always been an important part of the betting game, so much so that bettors in the pre-internet days were willing to hire spies on the scene. But as sports betting has spread across the country since 2018, meteorologists have seen an increased demand for earlier, more precise forecasts.

“With sports betting going on, that’s just opened up the floodgates to more people being interested in sports weather,” said Kevin Roth, a self-described “sports meteorologist” at daily fantasy website RotoGrinders.

Games played in extreme weather pose a question for bettors and meteorologists alike: Could the weather be an edge?

On Jan. 7, when the Jets played the Patriots, Ben Knott saw Roth’s forecast for “heavy in-game snow and winds gusting over 40 mph,” and decided to take a shot. The 21-year-old New York native wagered $2.82 on no player getting to 40 receiving yards.

He won $256.62.

“I tried to put like five dollars on it,” he said. “But DraftKings only let me put $2.82 on it.”

Bettors today aren’t seeking qualitative statements about the conditions outside, but quantitative analysis.

“They don’t want, ‘It could be a little wet,’ or, ‘It could be a little breezy,'” Roth said. “They want to know, ‘There’s been a 20% decrease to passing. There’s been a 32% decrease to home runs because of this wind orientation of past games.’ That’s the data that folks now want to know, and that sharp bettors are using to their advantage when weather matters.”

At Bettor Weather, Abramyan and her team publish analyses of the weather’s impact on games in college football, the NFL, MLB and MiLB. Each week, they scout areas of the country that might have weather impact before the betting lines are out and fine-tune their analysis as the weather develops. Their formula, or “the secret sauce” as Abramyan calls it, uses various factors like precipitation, wind speeds, cross winds and orientation of the stadium to calculate its impact on the game’s passing production, kicking and punting, to name a few. They then publish an analysis ranking the weather’s potential impact by the game’s quarters or halves — and the edge to be gained from it.

Abramyan quickly saw the impact of Bettor Weather’s work after it launched in summer 2022.

“As soon as we would put something out, [people using the website] would run and place the bets,” Abramyan said. “And they would actually move the line because they were putting so much money down. By the time we were able to bet it, to put our money down, it’s already dropped from 44.5 to 43 or something.”

Sportsbooks are also trying to keep up with the weather, but Chris Bennett, sportsbook director at Circa Sports, said he does not have a meteorologist or weather consultant on staff. “In practice, it’s almost impossible for the sportsbook to really put themselves in a good position and to be ahead of every customer on the evolving weather forecast,” he said.

Before the internet and advanced forecasting made detailed meteorology reports widely accessible, bettors came up with more creative ways to stay on top of the weather. In the late ’90s and early 2000s, a man sat in the bleachers near the outfield at Wrigley Field during batting practice on game day. Sure, he liked the Cubs, but mostly, he was there to watch the American flag.

Over the years, other men took his place. But their purpose remained the same — watch the flag, feel the wind’s direction and see how it’s affecting batters. That information would then be reported to bettors in Las Vegas, including Steven “Fats” Diano, to factor into their wagers.

When the internet rolled around, Diano could access a camera showing the outfield via Wrigley Field’s website. But there was a problem.

“You couldn’t get the camera high enough in the bleachers to see the flag,” Diano said. “That’s the only thing you couldn’t see.”

And so, the men in the stands remained. But the camera allowed Diano to keep an eye on things.

“We would call the guy one day ’cause we want to make sure he’s really there,” Diano recalled. “Go to center field. Go to the row right by such and such. And hold up your hand with three fingers, or somethin’. So, we would zoom in, and there we go — we’d see him holdin’ up three fingers.”

One day when the Cincinnati Reds were in town, the weather watcher told Diano that the wind was blowing in when the expectation on the totals was that it was blowing out. Diano couldn’t recall exactly how much they bet on the game, but said it would have been about $10,000.

But when the game began, the wind was indeed blowing out. The weather watcher had guessed, and no one had checked the camera.

“That was the last time,” Diano said. “We just said, ‘That’s the end of that.’ We’re done with Chicago.”

Before the game was moved, Bettor Weather’s recommended edge was a “strong under” in the Steelers-Bills game.

“If they already were liking the under in that game, use this to kind of push you over the edge,” Abramyan said. “If they liked the over in that game, then maybe it’ll be a stay away game.”

Professional gambler Bill Krackomberger was taking a different approach: Wait until kickoff, and when “the sportsbooks are forced to over move the line,” bet the over unless there are strong wind gusts.

Abramyan noted that these extreme weather games are tough to bet on because the sample size of similar games in the past is so small.

“You could do all your homework and have good confidence in what the weather’s going to do,” she said. “But as far as how it impacts the game, at the end of the day, you still only have a handful of games that have been played that fit that specific criteria.”

But as a bettor with 30 years of experience, Krackomberger embraces uncertainty.

“I’d rather have situations like that every week, because I know so much more than the public what to look for,” he said.

“It’s an overreaction to people just seeing snow. They don’t realize that really that doesn’t mean too much.”

ESPN staff writer David Purdum contributed to this report.