In reply to Joseph Howell:
In my opinion there are too many variables to answer with any confidence. For example further variables include what you have eaten and drunk, how tired you may be, what other clothing you may wear and personal metabolism.
Being in a tent will help, as will your insulating base mat. The data you have provided suggests you should be ok but I really don't know. You may find the following will help:
- Eat a hot and preferably fatty meal before you go to bed
- Do some sit ups when you first get into your sleep system
- Boost your sleep system by putting any spare jacket / clothing over the top of your sleeping bag
- Have a hot drink
- Possibly wear a hat
- Camp somewhere sheltered from the wind but not in a cold air hollow, ideally where you will get the first rays of sunshine in the morning