Originally Posted by
Erick L
There's your problem. Look for a pad with a R value of around 3 or more.
An uninsulated pad will let the ground suck the warmth out of you. It's not pleasant. You might want a little more insulation to keep you warm. You can buy another pad, or you can use a supplemental closed cell foam pad. When it comes to real cold weather camping, I'll use an insulated air mattress and a Thermarest SOLite underneath. It's enough to keep me warm down to about 0, with an appropriate sleeping bag.