OP here. Thank you!

OP, ask the nature center staff. They've done this plenty of times and probably in inclement weather so they'll have the answer.

I don't know the specific centers you cite, but one near us (not Arlington area) has some indoor exhibits (snakes, turtles), a big corner area with puppets and stuffed animals the kids can use, etc. But as others note above, those are not things "run" by rangers and you would need to be prepared to have enough parents present to keep the kids engaged looking at things.

Possibly for an extra fee the staff will arrange things beyond the ranger talk. Ask.

Anonymous wrote:I went to one of those centers for a 4th birthday party. Kids were inside the whole time, and they looked at exhibits, played musical chairs, freeze dance, ate, did a craft, etc. kids had fun.

As someone whose done a party there, just want to be clear to OP that you have plenty of space to do these activities but the parent has to plan and run them. The rangers only do the 30 minute animal show and you have a staff person to help with room set up.

My son has a winter birthday,,and we did a party at Potomac Overlook. It's all inside, except for one bit where they take the kids over to the bird house for a few minutes. It's fine.

I went to one of those centers for a 4th birthday party. Kids were inside the whole time, and they looked at exhibits, played musical chairs, freeze dance, ate, did a craft, etc. kids had fun.

I had my DD's 5th birthday at Potomac Overlook and could tell 1 week out that it was going to be rainy and would need to come up with inside activities. There really isn't much for kids to do inside there. Since she was really into Littlest Pet Shop at the time, I got a big refrigerator box, cut out doors and windows, and drew on a "pet shop" design with black marker. Brought that to the party along with a lot of markers and stickers plus stuffed animals. The kids had a ball decorating the pet shop and playing in it. We also brought face paint and painted kids as different animals. That was plenty to fill the time.

Another option to consider is Hidden Oaks Nature Center in Annandale they have a great playroom (and a wonderful outdoor natural play area if the weather cooperates) so you could just let the kids loose for free play there.
http://www.fairfaxcounty.gov/parks/hidden-oaks/birthdays.htm

I'm looking for a birthday party venue for a kindergartner and am considering a nature center. Birthday is in March, so the weather could be nice or could be cold/rainy/snowy. The places I have looked at have a 30 minute presentation by a ranger. If the weather is not good and we have to stay indoors, would there be enough to do indoors after the presentation? I'm in Arlington and looking at Potomac Overlook, Gulf Branch, and Long Branch.