Other than straw hats, Comet Gain, wild strawberries and bare feet in the white sand, the best thing about summer is Sangria. To make the perfect one, you will need:
1 litre of dry red wine (in my experience, Merlot works perfectly)
1,5 cups of orange juice
1 cup of pomegranate juice
0,5 cup of cognac
1,5 cups of club soda (nothing wrong with a colourless soft drink like Sprite)
0,25 cup of sugar
+ slices of peaches and apples and oranges or whatever else you will find at hand
And music, of course. "I'm Not Worrying" by Clarence Williams & His Kings would be a good start: