"In case" is usually followed by someone or something, like "Take an umbrella, in case you need it" "Wear sunglasses in case it gets too sunny out" "I write down everything the teacher says in case I need it later" But "in case of" is usually followed by an object that is causing something, I think most often natural disasters, such as: "In case of natural disaster" "In case of high winds flights will be cancelled" "In case of flooding locate your nearest PETA stadium" and so on. The first is usually in a more casual context, like you telling someone to do, take, or grab something. The latter is usually in a more formal context. You can also say "in the case of" or "in the case that" and those are used pretty much the same as the second.

same meaning, but different grammar around it: in case + verb --> in case it rains in case of + noun --> in case of rain

They are very similar. "Just in case" is for things that are very unlikely. "In case" is for something that may happen. "Use this in case of a fire." "There are robbers around here, I lock my door just in case."

"In case of" emergencies "In case of" robbers "In case of" disasters - directed towards nouns, specifically something bad "In case that" something happens "In case that" he comes - noun + verb Just "in case", we'll lock the doors - to prevent something from happening Overall, in case just means to prevent something not preferred from happening