Senior producer Paul Jeal said that rain will now be more unpredictable and can occur on specific sections of the track rather than the whole course.
"In F1 2010 we had a pretty awesome weather system, and it looked great in the way it transitioned from one to the other," he revealed at a behind-closed-doors presentation attended by Digital Spy.
"Perhaps it was too linear in the way it moved through, it wasn't randomised enough. It was either entirely wet or entirely dry across the whole track. This year, we've got the ability to rain on a particular section of the track.
"You can also see the storm fronts coming in now, your race engineer will tell you that rain's on the way, it's ten minutes, five minutes away, then it might divert away from the track completely."
He added: "You might not get any [rain] or you might have committed to new tires, so that mixes up the racing quite a lot."
F1 2012 will feature all the latest teams, drivers and circuits, including the debut of the Circuit of the Americas track in Austin, Texas and the return of Germany's Hockenheim circuit.
Codemasters recently revealed a sequel to the BAFTA-winning GRID.
The publisher is also working on free browser game F1 Online, which entered open beta yesterday (August 15).
F1 2012 will be available on Xbox 360, PS3 and PC on September 21 in the UK, across Europe on September 20 and in North America on September 18.
> Read our review of F1 2011 (PS3)
> Read our review of F1 2011 (Vita)
Watch the Champion's Mode trailer for F1 2012 below: