Weather arguably impacts baseball more than any other team sport. Most people realize that rain and wind make a difference, but other factors such as humidity and wind direction can also significantly influence a baseball game. Let’s take a look at some of the different weather factors FantasyLabs tracks and see what type of impact each factor has on hitters and pitchers.

Temperature

What Is It?

We’re looking at temperatures when games start. Indoor games have a default temperature of 72 degrees. The coldest game in our database since 2014 is 32 degrees, and the warmest is 102.

Impact on Hitters

Higher temperatures have produced value for hitters over the past three seasons (in Plus/Minus):

Per our Trends tool, we see that temperatures above 70 degrees have historically resulted in positive Plus/Minus values for hitters; temperatures below 70 degrees, negative values for hitters. Of course, hitters can still have big performances in cold weather, but in general it’s best to look for hitters in warm games.

Impact on Pitchers

Only 64 pitchers have pitched with a temperature between 31 and 40 degrees since 2014, but it makes sense that they would struggle in cold weather, as the ball would likely be harder to grip and control. In general, 41-70 degrees seems to be the productivity wheelhouse for pitchers. The weather is cold enough to prevent batters from having a temperature edge but not cold enough to interfere with the ability to throw the ball. Over 80 degrees, pitchers have been especially brutal.

Humidity

What Is It?

Humidity represents how much water vapor is present in the air. High humidity makes the weather feel warmer than the actual temperature, while low humidity makes the weather feel cooler.

Impact on Hitters

Hitters have generally produced more value with lower humidity, which is surprising, since air density decreases as humidity increases and base balls can travel farther with less air density. Humidity is still an important factor in evaluating weather, but it’s possible that the larger effects of humidity are masked by other weather factors as well as ballpark dynamics.

Impact on Pitchers

Pitchers have been at their best in games with a very low humidity, and that makes sense, because the air is at its densest, but the performance data outside of the bottom quintile makes little sense. Humidity is still useful in determining the weather’s effect on players, but it likely should be used as a component of a larger metric — like our Weather Rating — than on its own.

Precipitation Percentage

What Is It?

Precipitation percentage is the percentage chance for rain during the game. This is perhaps the most widely used weather metric in MLB, and it’s very important to monitor for both hitters and pitchers. Precipitation percentage can be monitored in our Player Models and on our Lineups page. We also provide notable precipitation updates via our MLB News feed.

Impact on Hitters

Hitters haven’t performed especially poorly in any of our precipitation quintiles. In fact, on the whole they’ve tended to provide some value with a moderate precipitation percentage: Air with a higher dew point will be less dense and cause baseballs to travel farther. Rostering hitters in games with a decent chance of rain can be scary, but it’s led to some value when the chance for rain isn’t too severe. The threat of a rainout always lingers, but rostering hitters in games with a decent chance of rain could be a contrarian move that leads to value and discounted ownership, which Pro subscribers can review in our DFS Ownership Dashboard shortly after lineups lock.

Impact on Pitchers

For pitchers, the possibility of precipitation is bad. They’ve historically returned the most value in games with little to no chance of rain but struggled in games with a chance of rain over 40 percent. Moisture makes the ball difficult to grip and the grass slick, a higher dew point makes batter balls travel farther, and rain delays are devastating because the starting pitchers are often pulled even if the game recommences. Accepting some risk for batters in games with a chance of rain makes sense, as they usually aren’t pulled from the lineup following a rain delay, but pitchers — especially in cash games — should likely be avoided if their precipitation percentage creeps any higher than 40 percent.

Wind Speed

What Is It?

This is the speed of the wind at the time the game starts. Wind speed defaults to zero if a game is played indoors.

Impact on Hitters

It’s clear that hitters historically benefit from high wind speed. (We’ll get into wind direction shortly.)

Impact on Pitchers

For pitchers, wind has historically produced negative value. Winds over 16 miles per hour have proved to be especially troublesome, as pitchers have posted brutal Plus/Minus values in games with the most-severe wind — but the direction of the wind also need to be taken into account.

Wind Direction

What Is It?

Wind direction indicates the direction the wind is blowing relative to the layout of the stadium. Wind coming “from” an area denotes wind that originates from a location, while wind blowing “to” an area denotes wind that is blowing toward that location.

Impact on Hitters: DraftKings

Impact on Hitters: FanDuel

Clearly this data needs to be contextualized, as many stadiums have their own established wind patterns, but in general hitters have thrived with wind blowing from left field, but the rest of the value has come from wind that isn’t blowing in. None of the Plus/Minus values in the wind direction images are especially high or low, but we can find value in combining this data with wind speed. For example, hitters have posted a +0.96 DraftKings Plus/Minus in games with winds blowing out over 12 miles per hour. Similarly, hitters have posted a -2.16 DraftKings Plus/Minus in games with winds blowing in over 12 miles per hour. Like most variables, wind direction is important but shouldn’t be relied upon independently of our other weather factors.

Impact on Pitchers: DraftKings

Impact on Pitchers: FanDuel

Unsurprisingly, pitchers have done best in domes and swirling winds and struggled with winds blowing out and to left field. As is the case with hitters, performance can vary greatly when this data is combined with wind speed. Pitchers have averaged a +3.45 Plus/Minus with wind blowing in at over 10 miles per hour, but they’ve averaged a -0.42 Plus/Minus with wind blowing out at over 10 miles per hour.

Weather Rating

What Is It?

Developed by FantasyLabs Co-Founder Jonathan Bales, Weather Rating is the percentile rank of how hitter/pitcher-friendly a game is. The metric is calculated using a model weighing specific weather factors and their impact on scoring. Basically, this one rating factors in all of the variables we have discussed and provides you with a percentage score between one and 100, with numbers closer to one being less player-friendly and numbers closer to 100 being more player-friendly. These is a position-specific metric, so a Weather Rating closer to 100 is good for hitters and pitchers.

Impact on Hitters

The ever-evolving Weather Rating helps determine what weather conditions are most optimal for a player, so it’s not surprising that a higher Weather Rating has led to more value for hitters. After all, that’s what it is designed to do. Targeting hitters with a Weather Rating greater than 80 has historically produced the most value.

Impact on Pitchers

It’s the same for pitchers. A middling Weather Rating between 20 and 80 hasn’t had a ton of impact on pitchers, but the extremes are noticeable. Analyzing the specific components of weather is useful, but so is managing your time and establishing an efficient method of performing DFS research. Weather Rating allows users to get a quick snapshot of a game’s weather, and it has proved to be more predictive than any of the other weather components in isolation.

Conclusion

Weather should always be considered when constructing a DFS lineup. Players are capable of crushing in suboptimal weather conditions, but aligning your lineups with weather factors that have historically led to value will give them the best chance of success.

Specifically, higher temperatures are good for hitters and bad for pitchers, higher precipitation percentages harm pitchers more than batters, wind speed and wind direction should be consulted in conjunction, and Weather Rating is the go-to metric for seeing how friendly the weather is for both hitters and pitchers.

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Be sure to use the FantasyLabs Tools for your own weather research.