Can a arrest warrant be issued over the weekend in IL?

Yes. A warrant for an arrest may be sought at any time of the day or night and on any day, may be crafted at any time, may be signed by a judge at anytime and may be executed at any time. There may be specific agency policies or state statutes for certain kinds of warrants, but otherwise, a warrant for an arrest could otherwise be served on a Sunday Christmas morning at 2:00 a.m.