Yes, they will get a little wet if they are made from water-resistant materials.
That means if an outdoor rug is not waterproof or water-resistant, it will get wet and even damaged when let in wet environments with heavy rains or snow.
Waterproof Outdoor Rugs
A waterproof outdoor rug will naturally repel water or any kind of liquid spills, hence such a rug can never get wet.
In other words, water is not absorbed by such rugs. One advantage of that is that the rug will not develop any mold or mildew smells. Check out this guide on how to clean rugs and get smells out.
Additionally, it will be easy to clean because its less prone to stains and dirt. This property is possible because the backing is 100% waterproof.
A waterproof rug will look beautiful and new longer even in harsh wet environments like floods. This makes such rugs ideal choices for high traffic areas, or busy offices and homes.
The most recommended rug material for such rugs is 100% nylon fiber which is a type of synthetic outdoor rugs.
Water-resistant Outdoor rugs
A water-resistant outdoor rug will absorb some water. The difference with indoor rugs is that a water-resistant outdoor rug will absorb less water and it will dry very quickly. You might need this guide on how to turn an indoor rug into an outdoor rug, so let me leave it there.
Therefore, such a rug can be left outside in the rain since it will only retain little water which will dry so quickly once the rain is over. Check out the best outdoor rugs for the rain in that post.
The most recommended outdoor rug material are polypropylene outdoor rugs. Such rugs are water-resistant, stain resistant, not color-fast and durable to withstand wet environments.
Olefin outdoor rugs and acrylic outdoor rugs are also other recommended rug materials for outdoor rugs. Read this guide on what material is best for outdoor rugs to get more tips on choosing water-resistant outdoor rug fibers.