We did a garden party for 7yr old DD in May on a day with on and off torrential rain 😂
We set up a couple of gazebos with an extra plastic tarp under the fabric cover to waterproof as much of the garden as possible. If rain is likely I strongly recommend a call out to friends asking to borrow some as they do make a difference.
Free play for the first hour, we had loads of bubble wands, chalks, balloons, balls, and a couple of the big garden games like connect 4 and ring toss. They just ran about like crazy things while we watched and intervened if things were getting a bit too adventurous.
Cooked up frozen pizzas for lunch and served with fruit, veg and crisps from help yourself bowls.
Pudding was ice cream sundae bar, so a scoop of strawberry, chocolate or vanilla icecream then they balanced as many toppings and sauces on that as physically possible.
Piñata followed by singing of happy birthday, blowing out of candles and a bit more free play till parents arrived to collect them.
They were all a bit damp from the rain and thoroughly hyped from the sugar but they had a good time.
We had a playlist on in the garden so whoever they ran out of things to play with they had a couple of minutes of disco dancing till they got distracted by something they saw out of the corner of their eyes.
The ones collected last spent a few minutes popping all the balloons they could find which was handy for clean up and lots of fun and noise, just needed to sweep the bits into a bag at the end.
For party bags they had a paper bag with handles filled with a slice of cake, whatever they scooped up from the piñata, a novelty hand sanitiser bottle, a bubble wand and one of those big plastic tube things that you twirl round and it makes a funny noise. I'd bought loads for them to play with at the party and it seemed a good way to get rid of them at the end.