i have worn them in colder temps, up to an hour outside just standing by my telescope in 30 degrees. toes got cold, but not unbearable. guess it just depends of the person. im sure getting the right size; toe socks can be used and the shoes are made of different materials for different uses.

http://www.vibramfivefingers.com/index.htm

I prefer the flow style. i have 1 pair of KSO and i wear them but i do like the flow better.