The shorter breathing system of the French bulldog is also what puts them at such a strong risk for "Heat Stroke". Shorter airways = less possibility of cooling the air which the dogs draws into it's body. Never, ever underestimate these dogs susceptibility to heat stroke. Limit their exposure to temperatures which you might personally find only mildly hot. Be conscious of the proximity to hot pavement.
NEVER leave a Frenchie in a locked car even in warm weather. They should always have lots of access to fresh water, shade, and cool areas to escape from the heat. You should always be alert and be prepared with the things you need to save your dogs life.
Just as it's cousin the English Bulldog, they are not good swimmers and can not take excessive heat or cold.