Don't remind your grown children to wear sweaters or carry umbrellas. It will drive them mad if you treat them as if they are still small children. It damages their credibility in front of their children and damages your credibility that you find fault with them. Remember that grandchildren have ears. They may be young but that doesn't mean that they are deaf.
Visits can be a delight or a horror.
The more carefully you plan ahead, they more likely they will be delights.