As the name suggests, the strange howling can be heard around Mount Chilliad and possibly around Blaine County. A video investigation of the mystery shows a strange howling, that changes periodically, at the Chiliad Tunnel, near the left entrance of the Paleto Forest. If player searches for the place the howling is heard from, nothing particularly interesting will be found.
It is unknown what creature makes this sound, since there are no wolves currently in the game (apart from Hunt The Beast an online game-mode.) Sometimes you can also hear another type of howling, but it sounds familiar as a dog yapping and players can hear it all over Blaine County.