Next time you pack, line the bottom of your suitcase with a new, large trash bag. Add your clothes, shoes, and accessories, and just before closing the suitcase, top it off with another new, large trash bag, making sure you wrap the bottom bag’s excess over the top bag.
Now, when your baggage is left on the tarmac during a downpour, your clothes have a better chance of staying dry.
The plastic bags also does double duty on the return trip: one bag holds dirty laundry, and the other covers the clothes again.