1/3 cup (75 mL) granulated sugar
In blender, blend watermelon with lemon juice until smooth. Strain into glass pitcher, pressing mixture; stir in sugar syrup. (Make-ahead: Cover and refrigerate for up to 1 week.)
Sparkling Watermelon Lemonade: Fill highball glass with ice. Add 3/4 cup (175 mL) Watermelon Lemonade. Top with 1/2 oz (15 mL) soda water; stir just to combine. Makes 1 serving.