It sounds like "penetrating" damp kat. A jargon word for water that comes laterally, straight through the wall. Simply, soaking through. Most constructions will take a lot of water, but recently, it's been exceptional.
As the wall (eventually ) dries out, it'll probably go. It would be a good idea to investigate in better weather. Sealant only as a desperate resort. You may well be able to see where it's getting in, with a good poke around.