How MLB stadiums are playing this season
Temperatures and other "Park Factors" provide interesting insights into how different ballparks affect offense in baseball
One of my favorite things about baseball is how external factors such as the stadiums being played in can have an outsized effect on a game. Unlike most other sports, the stadium dimensions and weather patterns during a game can literally change outcomes1.
And now that summer is in full swing as we’ve just passed the All-Star break, I wanted to take a look at how the different ballparks in MLB have been playing this season.
First, let’s look at how game-time temperatures at all 30 ballparks have been trending in the first half. The below graphic is sorted by highest average temperature to lowest in each team’s home games, as of the All-Star break.
Chase Field in Arizona has the highest average temperature — at least when the roof is open. Other retractable-roofed stadiums in the southern part of the country, such as loanDepot Field in Miami and Globe Life Field in Texas, also boast warm average temperatures. Although they would be even hotter if more than half their games weren’t played with the roof closed.
On the other end of the spectrum is Oracle Park in San Francisco, as well as a host of others in parts of the country known for cold weather in the beginning of the season. Of all the ballparks in the majors the Giants have the only one with a decreasing trend in average temperature as the season wears on. If you’ve ever spent summers in San Francisco, or are at least familiar with the famous Mark Twain quote2, you understand why.
Both of Chicago’s stadiums — Wrigley Field and Rate Field — are also near the bottom of this list due to those early-season cooler temps, but as the warm and humid Midwest summer months drag on those stadiums will move up the rankings.
The two newest stadiums, George M. Steinbrenner Field in Tampa, Fla. (home of the Tampa Bay Rays) and Sutter Health Park in West Sacramento, Calif. (home of the Athletics, formerly of Oakland), are among the top-four warmest ballparks so far this season. The Athletics’ park in particular is proving to be a hitter’s paradise also (more on that below).
Temperature is interesting to track because it’s an important factor in how different stadiums play throughout the season. More home runs are hit in the summer months across the league when the air is warmer, and in general, offensive output is elevated this time of year versus the colder months.
However, temperature is not the only component that affects run scoring rates in baseball. Other environmental factors such as humidity, air density and elevation determine how a ball will travel when pitched and batted. And, more obviously, the dimensions of the ballpark matter, as well as the surrounding buildings and structures which can influence how well the ball carries.
According to the Baseball Savant’s Statcast Park Factors3 metric, which attempts to put a single value on these park effects, Coors Field is the most offense-friendly ballpark in MLB. That shouldn’t be a surprise as Coors is located nearly a mile high in elevation in downtown Denver. As an example, a ball hit 380 feet in a stadium at sea level like Fenway Park will travel nearly 400 feet at Coors, which can be the difference between a warning path flyout and a homer.
With these different factors taken together, Sutter Health Park in Sac is proving to be the second-most hitter friendly park behind Coors Field so far this season. The A’s stadium is producing about 10 percent more offense than the average MLB park.
The aforementioned Oracle Park has always been known as a pitcher’s park. This season it’s seeing about two percent less run scoring than an average stadium so far. Part of that is the cool summer time temperatures, but it also has the highest air density4 of any of these ballparks thanks to its proximity to the chilly bay. The higher the air density, the more pitches move coming out of a hurler’s hands and the harder time a ball has getting out of the park off a bat. That combined with large dimensions in center field make it a haven for the guys on the mound rather than in the batter’s box.
The Texas Rangers’ stadium has also been a curious case the past few seasons. Globe Life currently has the most difficult run-scoring environment in the majors, seeing 11 percent less offensive production than other ballparks (Statcast Park Factor of 89). That’s funny because as we saw earlier it is among the warmer stadiums (when the roof is opened) and has relatively high humidity even with the roof closed (only so much air conditioning can do in the Texas summer with 40,000 fans inside the building). More interestingly it also used to be a hitter’s park — in 2023, the year the Rangers won the World Series, it boasted the third easiest run scoring environment.
“Our people are perplexed,” Rangers general manager Chris Young said to The Athletic last month. “We’re looking at everything from the humidor to which doors and windows are open at what points of time during the game for entrance and egress. We don’t have answers right now.”
Not all months in all stadiums are created equal either. Based on analysis done using 2024 data by Fangraphs’ Kiri Oler, parks play pretty differently in the summer versus the cooler spring months.
You can see certain stadiums deviate quite a bit from their overall Park Factor measurement depending on what month you look at. Stadiums that get warm and humid in the summer like in Chicago or Boston see an uptick in run scoring in June and July. While those that start off cold in the early months of the season like in Minnesota or on the East Coast make it really difficult on hitters in April and May.
Check back in by season’s end where I’ll update on how these trends in temperature and overall run scoring change for MLB stadiums.
Happy Summer everyone.
Remember Tal’s Hill in Houston?
“The coldest winter I ever spent was a summer in San Francisco”. Interestingly, the quote is likely a misattribution to Mark Twain, according to the San Francisco Examiner. While he did spend a summer in San Francisco and wrote about the weather, there's no evidence he explicitly said those words.
Park Factors, as calculated by Baseball Savant, quantifies how a baseball stadium affects offensive statistics like hits, home runs, and runs, relative to the league average. They're expressed as a percentage, with 100 representation the MLB average. So a park factor of 110 for home runs means that stadium produces 10% more home runs than the average MLB park.
As Alan Nathan has written in his research on the physics of baseball, the run-scoring conditions of a stadium are, to some degree, a function of its air density. “The important thing to remember about both the drag and Magnus forces is that they both are proportional to the density of the air. If baseball were played in a vacuum with no air, these forces would be exactly zero. But baseball is not played in a vacuum and there are wide variations in air density at different altitudes. Higher altitudes mean lower air density. Higher temperatures also mean lower air density.”