I would use the thinnest batting I could find.

Never too hot to use! We keep our home 70* year round. We live in New York state, where it's cooler most of the year. Even in the summer we've snuggled under our rag quilts that are made with flannel and 100% cotton batting through out most of the year!

Please post a picture when you're finished! Can't wait to see it!

I think it will be fine. I grew up in Oklahoma and I remember that it was very cold up there. I left out a batting on a flannel quilt I made and I have been sorry ever since. It is just so flat and doesn't show off the beautiful fabric at all.

Thanks to everyone who encouraged me!! Almost finished basting and will start quilting today.... staying inside during an ice storm (well, thankfully, the storm hasn't been nearly as bad as predicted...) is truly a blessing!!

My sentiments exactly! and with flannel on the back, it won't slide off the bed as easily either!

--and in the feeddogs, too. I have more trouble with it packing there than in the bobbin case. Your machine can use a good cleaning when you finish this project. Dampen a qtip to run around under the bobbin and all so you can pick up the lint on it. Love flannel quilts. Remember that's what she has requested so go with it.

I've made many raggy flannel quilts with 3 layers of flannel, no batting. Don't know if I'd want one on my bed but great for lap quilts or throw size. In fact I'm using one right now as I'm writing this, and I'm in Florida!

I have a king size flannel quilt with warm and natural batting. It is heavy. I live in sunny Southern California. You would assume that I would not enjoy using it, but I do. I pull it out around December and enjoy using it until about March. I am not a fan of heated air. It kills my sinuses. I sleep in a cool room and I sleep like a hibernating bear when I use my heavy quilt.

I will reiterate momsbusy and say to make sure she's willing to live with the weight. I did a rag quilt in flannel animal prints (tiger/leopard/zebra) and used black flannel on the back. If making again, I'd probably forgo backing or chose the lightest I could find.

I make flannel quilts all the time, we like our quilts to be warm. I love flannel for backing. Makes a soft, cuddly quilt. If that's what she wants it's what I would do, after all, it's for her.