Warm weather equivalent of “bundle up”

Question

When it is cold outside, parents inform their children that they should "bundle up" to dress properly for the cold. What is the warm-weather analogue to this phrase, that would be used to inform their children that they should dress properly for the heat?

Answer 1

You could say "Dress lightly for the heat."

For example,

Heat exhaustion is dangerous and can lead to Heatstroke, a life-threatening condition. It helps to be equipped with knowledge of preventative measures. Here are a few tips that will help you and your loved ones stay safe in the Georgia heat.
Dress Lightly
You already know that less is more when it comes to summer attire. Wearing lightweight clothing instead of heavy winter garments is a given. Plus, natural fibers such as cotton, linen and silk, especially in loose-fitting clothes, keep you more comfortable as they allow your skin to breathe, enabling perspiration to evaporate more easily.

Answer 2

You could say

It's going to be hot. Wear loose, light clothing to stay cool | avoid sunstroke.

There's nothing similar to the phrasal "bundle up" except perhaps strip down but that phrase is often used with taking everything off or everything but underclothing off, so it might be misunderstood.

Here’s the thing — dog’s have fur coats. They wear them all the time. They can’t strip down in the heat.