The fire from a wraith's attack is put out by rain making them a cakewalk during wet weather. Perhaps they should avoid spawning when it's raining similar to endermen?

Wraith Fire, according to the Wraith's entry in the Minecraft Dungeons wiki, is actually "ice flames". Due to this revelation, I have "inverted" the Wraith Fire to deal Frost damage and not be extinguished by water or rain. It will, however, be extinguished by fire.