You know the temperatures are oh-so-very cold when zoo employees decide to keep the penguins indoors.

Yes, these birds that recognizable for their tuxedo-like appearance and general inclination toward Antarctic conditions are having their outdoor time restricted by the Calgary Zoo in Alberta.

"We just don't want to expose them to too much," Malu Celli, a curator at the zoo, told Canadian Press. "To keep them safe, we decided to pick a limit to let them out."

The zoo keeps penguins indoors if the temperature dips below minus 25 degrees Celsius (minus 13 degrees Fahrenheit).

Celli says temperatures have averaged minus 28 C since before Jan. 1, but it felt like minus 40 C with the windchill, and that's too chilly even for these penguins.

Surely, however, it must get colder where these penguins are naturally located, right? Well, not so fast.

The Calgary Zoo hosts a range of penguins, including gentoos, rockhoppers and Humboldts. It also has king penguins, the smaller cousins of emperor penguins. None of these species, however, are fans of Antarctic conditions. Indeed, even the king penguins prefer subantarctic temperatures.

"It's not necessarily that it's too cold for [the king penguins]," Celli said. "I believe that physiologically, they can withstand colder weather than what we have here, but these are not wild birds."

The king penguins normally spend the winter months in an open-air enclosure and occasionally, they take a tour around the zoo's grounds and greet visitors, as you can see in the video above. However this year, the flock does have a chick that is still maturing, so the zoo is making sure each of its penguins stays hale and hearty.

Other exhibits in the zoo have made similar adjustments because of the cold, but if you're a human and wish to face the cold, you can take in the zoo as a winter wonderland.

"If you are brave and you come to the zoo, you're pretty much going to get the zoo all to yourself," Celli said.