Why do I have flowers but no fruit on my watermelon?

Watermelons have both male and female flowers on the same plant. Male flowers usually open first and female flowers have a baby fruit behind the flower. Both types of flowers must be present to have fruit set. Flowers may abort because of heat or cold or drought stress OR flowers abort because of a lack of pollination OR the plant is not ready to set fruit and the plant is self-aborting flowers to conserve and direct energy towards more growth.