Taking baby out in the summer

So I live in Northern Minnesota and my baby girl is 6wks and it’s been really hot lately!! My husbands family is all here and mine is in Florida, his family likes outdoor stuff and they like taking our baby girl outside when it’s super hot and I just worry it’s too hot for her, I’ve expressed my concerns about taking her and keeping her out for a while but they do it anyway sometimes... how long do you think she should be out or how long do you keep your little babies outside?