Weather can change how a game is played, and so its total and its kicking. Of everything in a forecast, wind matters most.
Wind
Strong wind makes deep passes and long field goals harder, and makes punts and kickoffs less predictable. Teams throw shorter or run more, drives stall, and fewer points get scored.
- Light wind makes little difference.
- Sustained wind of around 15 mph and up is where passing and long kicks start to suffer.
- Gusts matter as well as the average. A steady 12 mph and a 12 mph wind gusting to 30 are different games.
- Wind direction matters less than its strength over a whole game, since teams switch ends each quarter.
Rain and snow
- Rain makes the ball slippery: more fumbles and dropped passes, harder footing. Its effect on scoring is usually smaller than people expect, unless it is heavy.
- Snow can slow a game down, but light snow sometimes helps offenses, whose players know where they are going while defenders slip.
- Cold on its own matters less than wind. It can shorten kicks, and some teams handle it better than others, but it is rarely decisive by itself.
Roofs
- A closed roof (a dome) means the weather does not matter.
- A retractable roof is opened or closed on game day, about 90 minutes before kickoff. Until then, treat the forecast as possible but not certain.
- An open-air stadium gets the full forecast.
Forecasts and the market
- Forecasts get much better close to kickoff. A wind forecast a week out is a rough guide; one the day before is much more reliable.
- The market reacts to forecasts quickly, especially in totals. If the forecast is well known, the total has probably already moved.
- The edge, when there is one, is in acting on a forecast change before the line catches up, or in a market that reacts too much to a dramatic forecast.
In Unitley
get_game_weather gives a game's forecast: temperature at kickoff, the highest wind, gusts and chance of precipitation over the game, expected rain and snow, and the wind direction, from the National Weather Service (US venues) or MET Norway. It says when the venue has a closed or retractable roof, and when no forecast is on file yet (games more than 7 days out). Each forecast carries its source's attribution, which is shown wherever the forecast is.
Names set like this are Unitley’s tools: what your AI agent, or the analyst in the web app, calls to get these numbers. See the docs