I had an electrician run Cat 6 to all the bedrooms in my older house, and he ran the cable all along the outside of the house (not buried). It’s a blue Southwire cable that I believe is rated for indoor use, and I’m worried it may be an issue come winter here in northern-Illinois. Should I be worried about an impending doom and if so what can I do to protect the cables.
Sun exposure (UV) will be your enemy. In places with lots, like the south facing portions, the cables will start to crack in about 3-5 years. North sides may last longer. Cracks alone are no big deal, but will start to allow moisture in the jacket, which will become an issue.
You can extend the life by painting them, but this won’t last either.
Ultimately, you need to have outdoor rated cables, which will last much longer. You can do this yourself, one cable at a time. Since you have time, you can do this slow and right.