“ When was the last time a character caught a cold or flu? Real people get them every now and again even with solid heating and dry interiors. Your characters are out in the cold and wet, and even inside is not always dry and warm. Imagine having to stop your dungeon crawl, sitting in a tight defensive position, while you all are feverish.”
“ A friendly human hunter has a talk with you about what you are doing here, and how is the weather. He advises you to not disturb the animals, tend to any fire you set, etc. This is actually a werewolf checking his territory, and if you are not to his liking, he may ambush you with his pack later.”
“ The members of the party has unknowingly been infected by a mysterious plague and have been spreading the virus for quite some time now while adventuring. They start to hear rumors of all the cities in quarantine after they travelled trough. Will they discover the source of this? Will people start to avoid them, try to kill them?”