I’m in SE Florida and keep a quilt (with batting) on the bed all year. In the hot summer months it still looks pretty on the bed. They will love it because it is a gift you made with love just for them.

I live in San Diego, CA now, and grew up on a beach suburb of LA. (Although I have lived the past 20 years in the South Pacific tropics and only moved back last year) It still gets cold at night, and with only maybe a month or two, I always use a quilt on my bed. I wouldn't worry about it at all. If it gets too hot during the summer for them, they can simply fold it down when they go to bed, but still use it to display on the bed. They will be thrilled-go for it-trust me!!

Finish the quilt and send it to them. And remember, in their life times, many people move often. He's already moved from CO to CA, what if his company opens an office or whatever in North Dakota? Or Virginia?
It does get cold here in winter, I'm still sleeping under a pair of nice warm quilts.

I live in San Diego ... A quilt is always welcome ...

my sister lives in california. She used quilts all the time. When it is warm they have the air on so it is freezing in the house all the time. Even if they won't use it all the time, a quilt is wonderful to look at.

Thank you all for your kind words. When my brother and I talk we never get around to the weather and how chilly the nights might be. The quilt has been quilted using Warm and Natural batting. They're coming home for a visit this summer, so I'd better get the binding on in case they show up un-announced!
Best to all,
D

I make a number of "Summer weight" quilts, having lived in Florida 23 years and Alabama the last 5 years. I use Grand Flannel in them.

I live in Southern California and it still gets cold here. We can even get down to 32 degrees in winter. I'm sure a quilt will be appreciated no matter where you live.