Sar5 - Unfortunately I couldn't - had commitments that evening I couldn't duck out of to hide in my snow cave <img src="/ubbthreads/images/graemlins/frown.gif" alt="" />
Temp wise, after I had finished building it and crawled in to rest for a bit my clothes started to steam - I estimate it was at least 5 degrees celsius warmer inside - probably a bit more because once inside there is no wind chill either.

ElCacaFuego - I would hope Colorado has plenty of snow!

Another lesson I learned this winter is the importance of ground insulation.
On one trip I used this setup

DPM Milsupr bivi - then bog standard foam sleeping mat, then a cheap inflatable trekking mat - then sleeping bag, liner inside the bag. This worked OK on a short overnighter but really was too bulky and heavy to take on longer treks. Then I just used the inflatable and it was miserable - deflating at 3am, ground sapping your heat is not fun. I will have to save for an alternative next winter - maybe reindeer fur!

This is another shelter I did overnight in - you can see the wind has mucked it around and I fixed it up before going to bed but a strong gust around 3am (why is it whenever I'm out sleeping around 2-3 I am awake?!) blew the part covering my head off and I had snow come right down on top of me.
Always wear a balaclava to sleep in!

Me dressed for the weather - wool all the way baby!