I'm in southeast Texas and I"ve used flannel in the place of batting and it works great. I haven't use fleece but I know some people that have and really like it. I can see where it would make a really soft quilt.

Fleece is fine for backing. It provides warmth and softness. Who could ask for more?

I use it for batting all the time, but have some pieces that I have been considering using as backing on kids quilts. Fleece as batting makes the quilt feel softer to me, a little more "pillow-y".

I used fleece for backing on a quilt for a teacher's son who was having chemo. It is a lot warmer than having just cotton fabric on the backside.
If you are wanting something lightweight have you considered putting a layer of white fabric in the middle? It would probably stop the backing fabric from being seen on the top and be a lot lighter.

Thanks for all your comments. Today I'm going to use it to back my quilt top. The top is lots of dark and bright colors, so I don't think it will show through. Still to make quilts with what I already have :)

I made a triple Irish chain and decided to put flannel on the back so I didn't use batting. I actually do not like how it turned out. The quilting stitch doesn't look as nice and the quilt is too flat looking for my taste. I live in the Texas Hill Country not too far from your location.

Don't you think the fleece might be a little fluffier than flannel?

Skipping the batting should be fine

I've made a lot of quilt using fleece and I don't add batting. We live in Colorado and everyone stays warm with them. Texas should be fine.

I have made all my DGKs quilts with flannel on the front and fleece on the backing, no batting, and they just love them. They are wonderfully washable, and wonderfully warm. Just do a lot of pinning when you quilt it, as the fleece is stretchy and shifts easily.

Maybe use fleece AS the batting?