It's not common for there to be so much rain in March.

I have seen this sentence in a book, can you tell me the meaning or function  of 'for' in it? Is it possible to say the sentence without for with no change of meaning?

Thanks a lot.

"for" is a complementizer.   It signals the subject of the non-finite clause.  "to" goes with "for".  As infinitive marker it signals the predicate of the non-finite clause.  The "for ... to ..." pattern is common after "it is/was/... (not)" + adjective.

It is important for you to study hard.  (you study hard > for you to study hard)
It was not possible for John to get tickets for the concert. (John gets tickets for the concert > for John to get tickets for the concert)
It is normal for there to be some residue on the machinery. (There is some residue on the machinery > for there to be some residue on the machinery)
It is important for there to be two guards on duty.  (There are two guards on duty > for there to be two guards on duty)

The "for" is required in these constructions.

CJ