So we melt old crayons into various shapes all year long in the oven, but because it has been so hot, we wanted to see if the SUN could melt our crayons. 100 degrees yesterday, and yes, the sun melted our crayons! Great science experiment for the summer! Tip: set a timer for 30-60 minutes so that you can go back outside and check the progress. Smaller pieces may melt better.