Warming Bottles on the Go

JC

Hey mommas! My son just started bottle feeding. Tomorrow we are going to an outdoor fall festival that's from 12-5pm, and my son will only take a bottle if it's pretty warm. How do I go about warming bottles on the go? The festival is an hour away, so we will be gone pretty much all afternoon and I doubt we'll have access to any electricity for a bottle warmer.

Thanks!