It can happen at any time of year....rainstorms or snowstorms....not much difference. And as another poster said..other people sometimes pack large quantities of liquids which can also break and soak not only their stuff but others also. I have used travel spacebags for years.....don't need a vacuum to seal them...just zip close them and roll the air out. Saves a ton of space in my bag and also the rolling keeps things less wrinkled. I've seen my bags sitting in a cart on the tarmac in snow waiting to be loaded in Philadelphia and yet, everything remains dry inside. And, even worse, several years ago someone else had packed glass bottles of baby formula in their bag, which broke and obviously my bag was next to or under theirs and my bag was completely soaked with stinky baby formula.....completely ruined the bag......which Disney compensated me for since it appeared to have happened on the truck from MCO to a Disney resort, not at the airport. But, everything packed in the bag was dry and perfectly fine........packed in my space bags.....no smell or anything.