I am making seashells out of candy melts and I am wondering if they will melt if its hot out?

They'll only melt if they're out in the heat.

Chocolate melts at about body temp (98 degrees F). So, if the cake is going to be outside for any extended length of time, the shells may melt.

Chocolate will melt even faster if exposed to heat AND sunlight.

If the cake will be kept in an air conditioned environment, just make sure you refrigerate the shells (or entire cake) before transporting it. Keep it covered in the vehicle and make sure the vehicle is as cold as possible.

Thank very much...