Temperatures hovering around -30 C, with an extreme cold warning and a wind chill that feels more like -45 C, convinced most Calgarians to hibernate indoors on Sunday.

But a group of 23 plucky (or, depending on who you ask, crazy) runners braved the outdoors in just their shorts for a 5K charity race.

The runners raised more than $30,000 for Inn from the Cold, which provides emergency shelter for people in need.

"Physically, I'm doing it because I like the challenge," said Nathaniel Ernst, the run's organizer.

"The homeless don't have a choice whether it's going to be cold outside or not … We committed to running for the cause, so we were going to run no matter what the weather was."

Gear was limited to just tuques, gloves, shorts, socks and shoes.

"It's pretty crazy, but I'm super impressed with their passion," said Kara Layher with Inn from the Cold.

Runners were outside for about 35 minutes. According to an Environment Canada weather warning, frostbite can develop in minutes on exposed skin when temperatures dip below -20 C, but Ernst said the group took safety precautions.

Ernst's parents turned out to cheer their son on — but they bundled up in parkas for the occasion.