Dad, Pregnannt mom, and a 15 month baby in Boulder in December

Why Boulder? Denver would provide more options for things to do inside at that time of year. A number of museums, some shopping, etc. As to weather it is a dice roll. Could be very nice and could be very cold. It just depends.

He could snowboard within a couple hours of Boulder -- Loveland or a small area just west of Boulder. Gone blank on the name. The major resort areas, Breckenridge, Keystone, Vail, etc. will be packed at that time.

Eldora is the small ski resort just west of Boulder - less than an hour's drive, much easier to get to than the major resorts off I-70. Denver is just a short drive, or even bus ride, from Boulder, so no reason you can't enjoy the sights of both places.

Rocky Mountain National Park is also less than hour's drive from Boulder and the east side from Estes Park is open year-round. On a sunny day, it's well worth the time to visit in the beautiful solitude of winter. Lots of elk and other wildlife will be more easily visible at that time of year.

There was an extensive and well written trip report just posted on what to do in Boulder/Denver, so search in the Colorado forum within the last week and you should find it to help give you some ideas of what to do and see.

we are staying with his family there. thanks

We were just in Boulder in October and the weather ranged from a record low of 15 and 4 inches of snow to a record high of 84 degrees. So I would think you could experience almost any type of weather. Bring layers and you should be fine. There are lots of places in the Boulder area to walk even with a young child. The Boulder Creek Path, Central Park, the Pearl Street Mall. On the Boulder Creek Path, the guidebooks talk about an underwater fish observatory behind teh Millennium Harvest House and the Kids' Fishing Poinds on the south bank around 6th St. They also recommend the Fiske Planetarium for kids. Boulder has a very large public library and, if you contact them, I bet they have programs for kids that you could go to and they might also have information about other activities for children. I would also check the Boulder website. As we walked around town, there were so many people with young children so I would guess you will be able to find activities, playgrounds, etc. for while you are there.