My son uses these pants skiing in -8 windchill weather and also 30 degree weather and is comfortable with both. He just wears a pair of thin Hot Chillys with them and stays warm.
The size is large, however. He is 10 1/2 and we have to double over the elastic waistband. Although waist does has the hook and loop expanders, the smallest size is not small enough for my son. My son is 68 lbs and about 4'3" so he is a little on the small size for a 10 year old. The pants are also too long but with ski boots they are fine.
I suspect that it is Spyder's sizing because his last pair of size 8 pants he wore for the last two years. At this price, however, I am hoping we will get three years out of the pants.

Wow, the service is fantastic. We ordered the pant from a different supplier and it arrived 3 weeks late and in the wrong color.
we re-ordered from this site and they arrived in 4 days and in the right color. The pant is a lot warmer then other Spyder training pants.. My daughter removed 2 layers of thermals with this pant. She was training in minus 18C TEMPS
Pant reccommended!
Site recommended!... the online realtime customer service chat is excellent through to the instant processing of my order. This is one Australian who is satisfied and will buy from you again