A crew member grooms the ice at Nationals Park the day before a game between the Capitals and the Chicago Blackhawks in 2015. Workers have been busy building a similar rink this week at Navy-Marine Corps Memorial Stadium in Annapolis, Maryland. (John McDonnell/The Washington Post)

National Hockey League fans expect to bundle up when they go see their favorite team take the ice, but once in a while they may pack a raincoat, too.

When the Washington Capitals take on the Toronto Maple Leafs on Saturday, the teams won’t skate in the climate-controlled Capital One Arena. Instead, they will take to an outdoor rink in ­Navy-Marine Corps Memorial Stadium in Annapolis, Maryland.

One constant worry throughout the years with these outdoor games is the threat of bad weather. The league has had to delay the start of just one outdoor game from early afternoon to night because of rain in 2011. (Another outdoor challenge has been glare off the ice from the sun.)

The weather forecast for Saturday is partly cloudy with a 25 percent chance of rain. The only thing the league and fans can do is keep their fingers crossed.

“We don’t have a concern for this game because it will be a nighttime start,” said Derek King, the NHL’s senior manager of facilities operations. “What we’ve learned is that if the weather changes, we’ll change with it as well. We’ll cover the sheet up with inflated tarps and do our best to make sure the ice will be ready.”

A Canadian native, King got his start in Winnipeg, Manitoba, where he managed a community ice rink while studying engineering — specializing in refrigeration. By 2004, he had climbed the ranks to chief engineer at Winnipeg’s arena, now called Bell MTS Place.


It will take round-the-clock work for a week to turn the U.S. Naval Academy’s stadium into an outdoor ice rink for one game. (James Heuser/Washington Capitals)

King is now in charge of maintaining the quality of ice sheets for the league’s 31 arenas as well as coordinating its growing slate of outdoor games.

The NHL’s first outdoor regular-season game was in 2003. Five years later, the league began holding annual outdoor games in football stadiums and at baseball fields, an effort that has now expanded to include multiple games each season.

Creating a professional-quality ice rink on a grassy field is a big job. A team of 200 workers — including the on-ice crew, electricians and pipe fitters — needs to work on special equipment nearly around the clock for about a week to prepare an outdoor rink.

Custom-made aluminum trays are laid on the field, and 3,000 gallons of glycol coolant, a chemical that helps cool and stabilize temperature, are pumped through the trays until they reach 22 degrees — the ideal surface temperature for NHL ice. Fine-mist hoses then spray tap water to slowly form the ice.

A game-ready indoor sheet of ice needs to be about an inch thick, but an outdoor rink needs up to two inches of ice thickness.

The piece of machinery that is essential to King’s team is a 300-ton-capacity refrigeration unit that removes heat from the surface of the ice sheet and keeps the ice at a constant temperature.

“The operation is exactly like what you would find in any NHL arena,” King said. “We’ve just had to make it all fit inside a 53-foot mobile truck.”

By the numbers

25,000 feet of electrical cable to power the components in and around the rink

20,000 gallons of water to create a two-inch-thick sheet of ice

350 gallons of water-soluble paint to make the ice white

200 feet by 85 feet are the dimensions of a regulation NHL rink

Correction: A previous version of this article incorrectly stated that a regulation NHL rink was 200 feet by 65 feet. The correct dimensions are 200 feet by 85 feet. The story has been updated.