Heidi Klum Wears Lingerie on Freezing Balcony in Sensual Instagram Video

Heidi Klum ain't phased by the cold ... stripping down to just red lace lingerie and stretching on a frosty balcony in a video she posted to Instagram.

The model and television star posted a clip to her Instagram Saturday ... running her fingers through her messy, dirty blonde hair out on the balcony -- with the top of her backside showing in a red thong.

After doing a few stretches, Heidi turns, grabs a big handful of snow and throws it just above the camera ... possibly at husband Tom Kaulitz, who we know is gallivanting around Aspen with her.

In her caption, Heidi asks her fans if they have a tradition for New Year's ... before admitting she's a sucker for red lace.

As you may know ... Heidi's an active skier -- sharing clips where she's carving up the slopes while hanging out in the popular celeb holiday spot.

Kaulitz -- Heidi's husband of five years -- loves winter sports too ... joining his better half on their skiing trips engaging in a little PDA while soaking up the brisk mountain air.