It's far from cold, infact I have been too warm too many times, but never too cold, the underblanket traps hot air in a pocket below you, you are in a sleeping bag, so another source of heat, and the tarp stops the hot air leaving above you, in an extreme situation I could put a heavy blanket over the bug net and cocoon myself,
I have slept in this set up at -7 and been perfectly fine, sleeping in just some base layers, I have also camped out in the snow with a mate, having 3 tarps between us, we had a huge area undercover with no snow getting in, and a open fire for heat and cooking.
I have tried tents a few time before and would nevr go back to one, stuffy in summer, wet and cold in winter and need almost perfect flat ground.
I can have my full set up unpacked and tied up ready to go in a tad over 8 minutes.