Aha! I think I've identified it as a spring peeper. Right?

Goin' with Gray Treefrog (Hyla versicolor).

Look at the photos I took in the post called Frogs on Pool Cover - same frog? I'm in New York, and these gray tree frogs are pretty common I think, though I have never seen one up close before. Did he make a loud chirping noise?

I'm almost certain it's a Spring Peeper. Check this photo and link from the University of Rhode Island. It describes the chirping we hear around our pool and the other characteristics of the one I found.

Here is a link that might be useful: Spring Peeper at URI

Sticking with Gray Treefrog. Big difference in "dark X" on SP back and "dark blotch" on Gray's back.

Here is a link that might be useful: Gray

I just joined, so I've been browsing. I know this was posted over a month ago, but thought I'd jump in anyway. It's hard to tell size from a picture, but it looks to me like a grey treefrog. Spring peepers are about the size of your thumbnail, or thereabouts, and grey treefrogs are more golf ball sized. Did you see the belly? They have bright yellow bellies.

We have the same one on our deck. I'm saying it's a Cope's Gray treefrog. We had tadpoles and some survived. We have a few smaller ones this year. I think it's great!!! Good luck.

100 % gray treefrog. There are actually two cryptic species in connecticut(i live in Norwalk, CT) Hyla versicolor & Hyla chrysoscelis. They can only be identified 100% by a DNA test. Their calls are also slightly different. They will soon be calling and breeding.

Here is a link that might be useful: CT Herpetology Blog