How long is whole milk good for?

We go out alot on the weekends and usually end up eating lunch or dinner on the road. Since not all places carry whole milk I usually stop at a store a grab a small bottle of milk for my 1 y.os but finding a place can be a pain.

Does anyone know how long whole milk stays good in a cooler bag with 2 ice packs? We live in a fairly hot state if that matters? The cooler bag can fit 2 sippy cups and 2 ice packs.. that pack is literally for baby bottles