Is A Foxhole During Winter Viable?

If there is no shelter around and you really need it (since it is cold and you'll need a warm shelter), would a foxhole be viable?

 

I was born and raised in a tropical country but I have seen war movies and documentaries having a foxhole in a snowy terrain. From the looks of it, the cold is not that much because the heat of the body is trapped inside the foxhole. There was one scene in a war movie where there were 2 soldiers in one foxhole maybe to utilize the heat of the body.