Babies and heat

I’m taking my kids including my 4 month old to the zoo tomorrow, the heat index is suppose to be 109 so I’m trying to prep up for baby. He has a sunscreen swimsuit he’ll be in and a stroller with a visor and a hat.... I’m packing a cooler for snacks for my other kids and i was thinking of putting some wet wash clothes in the cooler so i could occasionally rub baby down with a cool cloth if i need too.... is this stupid and does anyone have any advice for braving the weather with an infant? Also, I’ve little was your baby when you took them outside with heat like this