Depends, there is a difference between saying you claim knowledge of the unseen (for example this person will die tomorrow at noon) or predicting a possibility which may occur in the future based on facts and info available to you (for example based on the direction the tornado is heading it is estimated that it will cause 2 million in damage expenditure!).
I would say to predict a POSSIBILITY of something which may occur in the future based on facts is not haram.
But if you claim that it will definitely happen then you are claiming to have knowledge of the Ghaib
“Say: “None in the heavens and the earth knows the Ghaib (Unseen)
except Allaah, nor can they perceive when they shall be resurrected”
“And with Him are the keys of the Ghayb (all that is hidden), none
knows them but He. And He knows whatever there is in the land and in
the sea; not a leaf falls, but He knows it. There is not a grain in
the darkness of the earth nor anything fresh or dry, but is written in
a Clear Record”
There are of course certain things which we can’t predict at all, such as judgement day, the anti-christ, gog and moug, death!