An hour, tops.

Not long enough to risk it. Without ice, a cooler is just an insulated box — it slows down warming but doesn’t stop it. In summer heat (90°F+), perishable food will hit the danger zone (above 40°F) in about an hour, maybe two if you pre-chilled everything and keep the lid shut.

The USDA rule is two hours total for food left out, and your cooler without ice is basically a sealed picnic table. If you’re thinking “I’ll just use frozen water bottles” — that’s still ice. No ice means no active cooling, just borrowed time.

This is not where you gamble. Eat it quick or keep it cold.