Outdoor activities in March - bad idea?

[notquitehuman]

My local park has just started renting a little pavilion type venue with a kitchen and a small room for parties. It's much cheaper than soft play, and I was thinking of throwing a birthday party for DS with a treasure hunt around the park.

Is this a terrible idea for mid March? It's been sunny the last couple of years on his birthday, and we managed to spend the day in a theme park last year. Should I just tell guests to bundle up or hand out umbrellas if it rains? The indoor space will be big enough for eating and maybe for pass the parcel, but not for a bunch of hyper 3-7 year olds to play!

[Lovelydiscusfish]

Sounds great to me - it's something a bit different, isn't it? Is there a playground too?