The afternoon heat can make it too hot at the beachside. Even if you are fine with continuing in the searing weather, chances are that your guests will not welcome such timing, especially when it comes to elderly people and children. Try to work around the heat and opt for a morning or late evening function. If there is no way you can have it at those times, go for the morning spot but ensure there is plenty of shade and breeze around to keep everyone cool. Keep an eye on the weather and pass on the weather forecast to your guests so that they can dress in accordance to the weather. You might also want to check up on the tide. A rising tide can be quite noisy and it can also creep up on your function half way through!