Relevant Fantasy Weather Data
Batters always seem to heat once summer rolls around. While some players may like to play in the summer versus the cooler months, the warmer weather also increases hitter production. Over the the rest of the year, our authors will be giving our readers a heads up for any possible games which may be hitter or pitcher friendly.
Weather has a significant effect on the distance a ball travels. In his book, the Physics of Baseball, Robert K. Adair noted a 10 degree temperature increase leads to an extra four feet on a 400-foot fly ball and each one mile per hour following wind speed means an extra three feet. For example, a fly ball hit at Wrigley field will travel 38 feet further on a day with the wing blowing out five mph and at 80 degrees versus an early spring day when the wind is blowing in five mph and the temperature is 60 degrees. This information shouldn’t be used to start Wade Davis over King Felix, but if an owner is deciding between a couple of similar players, it could be used as a tie-breaker.
Starting with temperature, I looked to get an accurate yet simple formula to see when the run scoring environment changes. Taking all the team scores from 2007 to 2013, I grouped them into five degree temperature ranges. Here are the findings:

Fewer samples existed under or equal to 65F, so I grouped all the values together and calculated the average value. Teams and their pitchers look to give up an extra run when the temperature is 100F or more versus when it is 65F or less.
The daily temperatures can be found at DailyBaseballData.com and our authors will be looking looking at publishing the extreme values when they occur.
Another run-scoring weather factor is the wind. I looked at all the stadiums when the wind was blowing out for a change in the run scoring environment. Not all stadiums were effected by wind because of design or local weather patterns. Here are the instances where the runs scored changed by 0.5 or more compared to the average.
| Wind blowing out | RS Diff |
| Chicago (NL) | +1.0 |
| Wind blowing in | |
| New York (AL) | -0.8 |
| Philadelphia | -0.6 |
| Chicago (NL) | -0.5 |
| Texas | +0.5 |
Today, I am just going to at the most extreme case, Wrigley Field. Finding a simple way to show the different scoring environments in Wrigley was not so easy. Two factors were at work. When the wind blows in, the average temperature is over 10 degrees cooler than when the hot summer wind is blowing out. Also, twice as many games are played with the wind blowing in than out.
I cut and diced the data way too many ways. Finally, I came up with the following chart for dealing with games at Wrigley:
| Wind Direction | R/G | AVG Temp. | AVG Wind | # of Games |
| Out >= 74 | 6.0 | 82.3 | 9.2 | 79 |
| Out <= 73 | 4.9 | 62.3 | 9.8 | 44 |
| In | 4.1 | 64.0 | 8.6 | 259 |
If the game is hot and the wind is blowing out, hold on for a high-scoring game compared to when the wind is blowing in. Again, our authors will give our readers a heads up if the wind is blowing out at Wrigley.
I am going to dig a little deeper to see if wind patterns affect any other parks. For now, games are generally being played in the normal zone as the temperature moves from cool spring temperatures to the heat of summer.
Jeff, one of the authors of the fantasy baseball guide,The Process, writes for RotoGraphs, The Hardball Times, Rotowire, Baseball America, and BaseballHQ. He has been nominated for two SABR Analytics Research Award for Contemporary Analysis and won it in 2013 in tandem with Bill Petti. He has won four FSWA Awards including on for his Mining the News series. He's won Tout Wars three times, LABR twice, and got his first NFBC Main Event win in 2021. Follow him on Twitter @jeffwzimmerman.
Rays and Jays should totally buy wind machines to selectively create favorable conditions depending on who’s pitching that day.
Any thought to if this info could be parlayed into a Roto strategy? For example, draft pitcher heavy in the spring and start trading off some frontline starters for bats as the weather heats up? Not sure if realistic but interesting nonetheless.
That seems very extreme. But it’s good knowledge to have when judging a player
I wish we could start simpler on weather and for me I’d just like to see a list of the day’s games and their % chance of rainout game/innings. For those of us playing daily games such as fanduel, this kind of information is both hard to find and yet supremely important. I’ll frequently email back and forth with friends as we’re all checking the hourly forecast for game locations.
The temperature run scoring change absolutely blows me away. To say that the temperature alone can change the run scoring environment by a run is a bold statement so I have to ask a few questions:
1) Did you use starting temperature or average game temperature?
2) Is there any correlation between temperature and wind?
3) Can you redo the graph, but change it from absolute temperature to a deviation from the average temperature in that park? My guess is that southern teams may have happened to be more offensive juggernauts in the time period you selected.
The further a ball travels or doesn’t travel can lead to a huge difference in a game.
The link between temp and run scoring is document in several ways, but the easiest is to look at the run scoring over the months.
From 2013
Month: OPS
Mar/Apr: .711
May: .730
June: .730
July .731
Aug: .725
Sept/Oct: .718
http://www.livestrong.com/article/272213-the-effect-of-temperatures-on-baseballs/
http://www.fangraphs.com/blogs/weather_and_park_factors/
http://www.predictem.com/mlb/weather.php (Vegas acknowledges the problem)