NFL betting and weather: how wind and cold affect the lines

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Weather matters most in NFL betting when it’s windy or very cold, and it shows up mainly in the game total. Strong wind makes passing and kicking harder, which usually means fewer points, and books lower totals as the forecast firms up. Any edge comes from reading the forecast better than the market does, or betting before the market has adjusted.

Which weather matters most

Wind is the big one. Brian Burke of Advanced NFL Stats studied how weather affects the passing game, using the wind speed listed in the official gamebook. He found that teams lean clearly toward the run only when the wind is above about 15 mph. Even in winds over 20 mph, the two offenses together traded only about five passes for runs over a whole game.

Play calling barely shifts on a breezy day, and it shifts much more in strong, steady wind. Gusts matter as well as the average speed, since a strong gust can push a deep pass or a long field goal off line.

Cold matters too. Burke found that passing efficiency drops as the temperature falls, and that cold put dome and warm-climate teams at a disadvantage. He also warned that very few games were played at the extremes, with only 36 in the 11 to 20 degree range.

Rain and snow get a lot of attention too. A wet ball is harder to throw, catch and hold onto, and heavy snow slows everyone down. How much it matters depends on how hard it’s expected to come down and whether wind comes with it.

How well the betting market prices weather

Betting markets react to forecasts, but academic studies have found gaps in the past. In a 2007 study in the Journal of Economics and Business, Richard Borghesi looked at 5,463 NFL games from 1981 to 2004. He found that game-day temperature affected team performance and wasn’t fully reflected in point spreads, and that bets on home teams playing in the coldest temperatures were significantly underpriced.

Rodney Paul’s 2017 study in the International Journal of Sport Finance compared actual scoring with betting totals. Humidity helped explain the gap between the two, and simple betting strategies based on humidity and wind speed gave results suggesting the totals weren’t fully pricing those conditions in. It also found that high humidity may lead to more scoring than expected through the running game.

Borghesi’s data ends in 2004, and once research like this is published, books can use it too. Assume today’s lines already account for obvious weather, and look for games where the forecast has changed faster than the number.

How weather moves totals and spreads

Totals react first. Say a game opens with a total of 44.5 and midweek forecasts start calling for 20 to 25 mph winds. If the book drops the total to 41.5 by Sunday, anyone who bet the under at 44.5 has three points of cushion that later bettors don’t get.

That only works if the forecast holds. If the wind dies down by game day, the total may climb back toward 44.5, and your early under has no cushion at all.

Spreads react less, because bad weather affects both teams. It can still matter at the margins. A team that relies on its passing game or a long-range kicker has more to lose in the wind than a team built to run the ball. And in a low-scoring game, final margins tend to be smaller, so each point on the spread counts for more.

Reading the forecast

Forecasts get more accurate as game day gets closer. According to NOAA’s SciJinks site, a five-day forecast is right about 90% of the time and a seven-day forecast about 80% of the time, while a forecast 10 or more days out is right only about half the time.

For a Sunday game, that means a Tuesday or Wednesday forecast is useful but can still change. Use the National Weather Service forecast for the stadium’s location, and check it again on game day.

  • Check sustained wind speed and gusts for the hours of the game, not the daily average.
  • Check whether the stadium has a dome or a retractable roof. A closed roof takes the outside weather out of play.
  • Keep in mind that wind can swirl inside an open stadium in ways a city forecast doesn’t show.
  • Look at who’s playing. Wind and cold mainly hurt passing, so a team that relies on its quarterback has more to lose than one that runs the ball well.

Be careful with weather trends

Say you see a trend like “the under is 8-2 in games with winds over 20 mph.” A sample of 10 games is tiny. A fair coin lands heads 8 or more times in 10 flips about 5% of the time, and if you look through 20 unrelated trends of that size, there’s about a two-in-three chance at least one of them looks that good by luck alone.

Before trusting a weather trend, check how many games it covers, which totals it was graded against (opening or closing), and whether it has held up in the seasons since someone first noticed it. A trend graded against opening totals can look much better than one graded against closing totals, because by kickoff the weather is already in the number.

Putting it into practice

Weather is one input among many. Start with your own view of the game, then adjust for what you expect the conditions to be. If the forecast is strong and settled, compare the posted total with your number, and bet when the gap is big enough to cover the price. At -110 you need to win 52.38% of your bets to break even.

Compare prices before you bet, since books don’t always move at the same time. Our guide to anticipating line shifts covers timing in more detail, and the three handicapping techniques of football shows where weather fits in a full game analysis. For more on how injuries affect the line, see injuries and the NFL point spread.

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Bovada lists NFL totals for every game, so you can see how its number moves as the weather forecast changes during the week. If you live in a state with legal online sportsbooks, a state-licensed book gives you more protection, because it answers to a state regulator if something goes wrong.

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