täysin sekaisin –
All mixed up or crazy. Or in this case, Miksi sää on täysin sekaisin? Why is the weather all mixed up? It could also mean why is it a total mess? Basically, it shouldn’t be this cold in March (still almost 10 below Celcius this morning in Helsinki), but it is, and a lot of people are complaining about it.
täysin (adverb) – absolutely, totally, completely, utterly, etc.
sekaisin (adjective) – mixed, confused, etc. Or even fucked up.