Assume the weather forecast underestimates the temperature, especially if you'll be riding past noon.

I aim for one bottle per hour. 1-2 should be an electrolyte drink, like Gatorade, depending on how long you are riding. Also you want to consume 200-300 calories per hour, and make sure there's some sodium in your snacks. Eat before you're hungry, drink before you're thirsty.

Make sure you are well hydrated between now and the ride, and it will probably also help to make the meal the night before on the salty side.

Where will you be riding?