The activities you pick to do at your picnic can make it a success or failure. Choosing which activities will be popular and which will not be is not particularly hard, however. Generally considering the location of the picnic and the weather will help you determine what toys or games you might want to bring to keep everyone happy.
If it is over a hundred degrees out and the sun is high in the sky without a cloud in sight, games that require a lot of running around will probably not be particularly popular. However, if your picnic area includes a pond or pool, the suggestions for a game of water volleyball would probably go over extremely well. If there is no water, a game of cards or poker in the shade might be popular.
On the other hand, if it is a cool sixty degrees out, the suggestion that people go for a swim will probably be quickly vetoed. This is the time to suggest a game of flag football or basketball or something of that sort. While people will still get warm, it will not be completely unbearable. A picnic stands a better chance of being successful if the activities are planned with the weather and park facilities in mind.
