Are there door knobs specifically meant for outdoors?

Locksets (including doornobs) are intended for either interior or exterior use. Some may be rated for both.

There are some differences in configuration (such as deadbolt vs. privacy lock) and differences in durability and sealing. Doorknobs and locksets intended for interior use may have no water seal and may use a thinner protective coating.

Doorknobs and locks intended for exterior use could easily be used indoors, but interior sets may quickly leak, corrode, or lose their finish if exposed outdoors.

Sooner, or later even excellent exterior lock sets will look bad, especially if you live near the ocean. I live 1/2 mile from the ocean and believe me, my exterior locks look very bad...and the rest of my home is in ship shape. Of course, my lock sets are now 17 years old...put in when the home was built. So I disagree with the above comment. My home is worth over a half million and I have the money to keep it up...but exterior locks near the ocean can suffer first. It pays to buy the best you can find and that means coated with rust repellent.

We have a place on Longboat Key that is 40 ft from the Sarasota Bay and less than a mile from the Gulf of New Mexico. I wasn't paying attention and our contractor put on 3 exterior doors a cheap Kwikset door lock sets on 3 exterior doors knob sets during our major renovation which are exposed to the elements. In less than a year all three are rusting. So I am in the process of getting warranty replacements, but moving on to a much better brand, Schlage. Better quality and better customer service.