I won a yeti tundra 65 earlier this summer. A couple weekends ago I loaded it up with two - 1gal frozen water jugs, lunch, some snacks and bottled water for a fishing trip on a Sat morning. Ate my lunch, snacks and drank most of the water. The cooler stayed in the back of my truck until I finally cleaned it out on the following Tuesday evening. The water jugs were still partially frozen even though that week was in the 90's and the back of my truck I'm sure was even hotter.

4 days still cold in the heat. Not bad especially considering the cooler was mostly empty....a full cooler stays cold the longest.