The 25-year-old linked up with the League One strugglers on Thursday morning.
Hall has made nine appearances - three starts and six from the bench – since arriving from Southend United last season.
Brian McDermott told the club website: “He could go away and do really well and might come back here and do really well, you never know.
“For me, he’s someone who plays off the strikers and we have El-Hadji Diouf and Ross McCormack who play there so it’s difficult for him to play here.
“Sometimes you have to let players go to get their careers up and running.
“He didn’t come back as fit as he could have done, but he’s been working hard and training well.
“I spoke to David Weir, who wants to take him and I think this is right for his career and is right for us.”