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Most football fans have seen the whitewashed games late in every season: a snow storm hits the stadium pre- or mid-game, and National Football League games are not postponed by weather so games must continue. For these very well-paid athletes, have you ever wondered if the league or teams do anything to help players in snow-drenched, freezing conditions?
Many NFL stadiums have fields that are heated underneath. Just over half of the 30 stadiums have some sort of heating system under the turf, whether that’s grass or artificial grass turf, to keep the playing field warm.
The main reason for this is player safety. Unlike other sports that also heat fields, like soccer, the NFL never cancels or postpones a game due to weather. Therefore, games are staged in freezing, and even sub-freezing, temperatures that can make the soil as hard as concrete.
Underground heating systems keep particles in the top layer of soil warm and loose, which allows the soil to compress adequately when heavy things (like bodies of football players) land on it. Think of the difference between concrete and the hard rubber coating under many playgrounds today.
There are other benefits from heating fields, too. The warmer soil also protects roots of real grass during extreme weather temperatures. And in at least 1 NFL stadium, the turf is heated at night specifically to prevent shock from the switch away from extremely high daytime temps.
Which NFL Teams have a Heated Field?
Many NFL stadiums have heating systems for their playing field: A little over half, or 16, to be exact. There are 30 NFL stadiums hosting 32 teams. Two are 2-team cities (New York and Los Angeles, where teams share a stadium).
How the field is heated, where, and how much so, differs from stadium to stadium, usually depending on needs of the region. Most heated fields in the NFL are in stadiums in cities on the northern side of the United States, where winters get super cold.
But not all. Allegiant Stadium in Las Vegas, home of the Raiders, has a heated field, mainly because temperatures at night in southern Nevada can get quite cold and threaten the health of field turf.
That turf is specially rolled outside the stadium when not in use, then rolled back in for usage. So … in very cold Vegas nights that turf would sit unprotected from icy winter temps and winds.
NFL Teams with No Heated Field
Only a single outdoor field in an NFL stadium is not warmed: that in Highmark Stadium, home of the Buffalo Bills. The reason there is, underground heating has been problematic for some types of artificial turf. However, plans are underway for a new Bills stadium by 2026 ~ with a heating system for the field.
Stadium enclosed by domes, of course ~ like in Minneapolis, or Detroit ~ also do not use or need field heating systems.
Do NFL Fields have Heaters Underneath?: Readers’ Inquiry
If the question is about heaters, like the ones indoors that we switch on to warm our house or office, the answer is no. But something similar heats some fields ~ only exponentially larger.
The Kansas City Chiefs in 2016 installed a $2.2 million heating unit underground. In actuality, they had installed boilers that generate 3 million BTU. For comparison, it takes up to 82,000 BTU to heat a 1,500-square foot house.
So there is a LOT of heating going on under Arrowhead Stadium via 4-inch-thick pipes ~all to prevent the playing field from freezing.
Where NFL Fields are Heated
Basically, about half of NFL teams are located in cities that sustain freezing, near-freezing, or even sub-freezing temperatures in the winter ~ which covers NFL games in December and January.
These are cities in the northern regions of the nation, places like Denver in the west, Kansas City and Chicago in the midwest, to all the teams up the Eastern seaboard: New York and Buffalo in the state of New York, in Foxboro near Boston, in Baltimore, Washington, D.C., in Philadelphia, Pittsburgh, and Cleveland.
Again, it’s not always a choice over regional temperatures. Stadiums for NFL teams use various types of turf on them, whether a variety of real grass strains, or various forms of “fake grass” (artificial turf).
It would seem that stadiums with real grass would most want the field warmed. But actually, it’s NFL fields with artificial turf that can have problems with underground heating systems.
While real grass can be sensitive to extreme sub-freezing temperatures, with their roots stuck in ice-cube like soil, it can survive, and as an organism is quite adaptable and self-renewing.
Not so for fake grass, made of plastic or other synthetic materials, which are prone to breaking down when bounced from extreme cold to heat and vice-versa. It’s about molecules and expanding and contracting; and fake grass doesn’t have millions of years of evolution to deal with it.
Damage fake grass, and it has to be replaced. So some stadiums, like that in Buffalo (at least until 2026) skip the ground heating system.
How NFL Stadium Fields are Heated
Most NFL field heating systems are designed via a network of pipes under the surface of the field. The pipes are connected with underground boilers away from the field that pump hot water through the pipes, which in turn warms the soil around them.
Of course, sometimes even the heated water in the pipes succumb to the freezing. Some groundskeepers even use antifreeze inside the pipes to prevent them from freezing solid!
Just like with our heating and cooling systems at home, these field heating systems produce excess water that has to be carefully disposed of. Heated fields have carefully engineered drainage systems, because all that piped water has to go somewhere eventually.
Many NFL stadiums go with sand-based systems through the root zone, to help better drain water, boost air flow through the soil, and help root growth.
Differences in NFL Field Heating Systems
As noted above, the level to which NFL stadiums heat their fields varies greatly. We already noted the 3-million BTU power in Kansas City. But some stadiums have systems designed more to heat the lines of the gridiron ~ so they can be seen in snowstorms.
Longtime NFL fans may have noticed this strange phenomenon in recent years, as a field fully white from snow somehow has green stripes throughout with a white line in the middle. Pretty ingenious, actually, don’t you think?
Which field lines, or how much of the field, is heated is dependent upon the heating system installed in each stadium. Some stadiums heat the entire field; others have heating systems only for the seats, which is good for fans obviously, but still contributes to protecting the turf on the field.
Aside from heating the seating, another tactic NFL stadiums use to protect the temperature on the field is overhangs, or huge canopies.
People may think the canopy at Seattle’s Lumen Field is to protect the fans from the constant rain there ~ the canopy covers about 70% percent of the seats ~ but it also contributes to keeping some of the moisture off the field of play, which helps manage the temperature overall.
By the way, the new Bills stadium to open in 2026 will have a canopy to cover about 65% of the seats. Amazingly, it will have a natural grass field, with an under-field heating system.
How Heated are NFL Fields?
Depending on the locale, from 38 to 60 degrees Fahrenheit. In Lambeau Field, the groundskeeper chooses 38 degrees as the target, which is above freezing but still cold so the grass does not get too soft to continue to thrive in that environment.
The warmest is in Philadelphia where the groundskeepers can bump the field temperature up to as high as 60 degrees. Others just shoot for around 50 degrees, kind of a happy medium.
Related Questions
Question: Which was the first NFL stadium field to be heated?
Answer: Lambeau Field in Green Bay, Wisconsin. Most NFL fans have heard the term “the frozen tundra of Lambeau Field.” Some of the coldest games in NFL history have been played there, including the NFC championship game on the last day of 1967 between the Packers and Dallas Cowboys that is forever known as the Ice Bowl ~ it was that cold.
Q.: How did they invent it at Lambeau Field?
A.: They installed a hydronic heating system, which means they buried pipes 6 inches to 1 foot under the turf, and filled them with warm water to protect the soil and roots from freezing. The system would be copied and implemented in other stadiums soon thereafter, including the original heating system at Arrowhead Stadium in Kansas City.
Q.: Why would they have to heat the football field in Las Vegas?
A.: Due to cold evenings there in the desert, the heating system at Allegiant Stadium prevents the soil from going into shock from shifting to very hot to very cold temperatures often. Allegiant Stadium opened in 2020.
Q.: What is BTU?
A.: It stands for British Thermal Unit, which is a measurement unit for heat energy. A BTU is how much energy is needed to raise the temperature of 1 lb. of liquid water by 1 degree Fahrenheit. So in the Chiefs stadium, the boilers there pump millions of BTU. You can heat a 1,500-square-foot house with 68,000 to 82,000 BTU.