Looking for a first birthday Party theme. Baby girl with a December birthday. DO NOT want to do Christmas or winter wonderland theme. But I can't think of anything else.
Humm... we went with a donut shop theme because we've been taking his montly photos with the huge, plush, stuffed donut... so it seemed natural. Anything you've done with her that she particularly enjoyed? or that you've done a lot of? Maybe do animals? I've seen rainbow themed parties that were very cute. Cute as a button using buttons everywhere... Super star/ hollywood... Circus.. honey bees, I have a friend who did a very "hoppy" first birthday and did bunnies everywhere... You could always just choose colors...
Ice cream social? (Kinda "frozen" but not "holiday?) Trust me... my B-day is Dec. 24th... so I get the no holiday/winterland thing... but ice cream could be fun.. and you could decorate with "sprinkle" primary colors and ice cream cones... etc..
For DD1 we had a pirate theme party. I made her a pink dress with skulls on it and all our family showed up in pirate gear, even without prompting. It was fun.
DD2 turns one in a month and I think I might do something generic like butterflies or flowers.
Snowflakes? If you want it to be a theme with a name/title and not simply for a consistent look in decorations, you could focus on her being special/unique. I don't see this as the same as "winter wonderland."
Something with mittens and hot cocoa could be cute. Remember the book, "The Mitten" by Jan Brett?