When something happens freakishly, it happens in a way that feels very far from normal — unusual, and sometimes a little frightening, as if the world has slipped. People often put it in front of an adjective: freakishly tall, freakishly quiet, freakishly lucky, freakishly good. Though actually, in that pattern it does not always mean “scary”. Quite often it means “so extreme you almost cannot believe it” — a kind of unnaturally strong degree. There can still be a shiver of “that’s not right” in it, especially with weather, silence, coincidence, or a face. It is a little informal, but newspapers use it too. It is the adverb from freakish: not a separate idea, just “in a freakish way”.