— Refrigerate all planned picnic foods so they're cold before you pack them in a cooler.
— Avoid putting coolers in a trunk. Instead, transport them in the air-conditioned passenger area of a vehicle.
— When you get to a picnic site, remove coolers from the car and set in the shade.
— Ensure all perishable food is kept in an ice-packed cooler until the moment you serve it. If the ice melts, the food should not be consumed.
— At home, perishable foods should not sit at room temperature for more than two hours. If outside in temperatures of 32 C (90 F) or more, reduce time to one hour.
— Never take home leftovers from a picnic. Discard any prepared food not eaten.
Source: Various.Suggest a correction