To make the cupcakes: Preheat the oven to 350 degrees and line to muffin pans with cupcake liners.
Sift the flour, baking soda, baking powder, and salt together in s small bowl; set aside.
In a large bowl, or the bowl of a standing mixer, cream the butter and sugar together until light and fluffy. Add the eggs, one at a time, mixing well between each addition and scraping the bowl as needed. Stir in the watermelon flavoring. Add about a third of the flour mixture and beat on medium speed until just mixed. Add half of the sour cream, beating until just mixed. Repeat this process with the remaining flour mixture and sour cream. Add color as desired.
Fill 2/3 batter into each cup of lined muffin pans and bake at for 20 minutes, or until a toothpick inserted in the center comes out with one or two crumbs clinging to it.