Another update ....
It's really a mixed message, unfortunately.
At 10AM, it's 76 degrees and humid in Champaign. Partly cloudy skies. South wind at 10 MPH. There's an area of light to moderate rain showers not far to the west, over Central Illinois this morning. While a few rain drop could sneak into Champaign over the next couple of hours, most or all of that precipitation should fade. Temperature this afternoon will likely top out over 80.
Here's the concern: There's a good chances a line of showers and thunderstorms (some heavy/strong) will develop over Western Illinois the middle of this afternoon -- then track eastward. About half the computer models diminish or completely dissipate the precipitation before it reaches Champaign, as it runs into an area that is still under the influence of high pressure. The other half of the models hold the precipitation together as it moves into Champaign -- somewhere around the time of kickoff (plus or minus an hour). Yes, good chance any rain that does reach Champaign (if it does) will include thunderstorms (lightning).
A weather model I rely on quite a bit for Texas forecasting is not at all kind for the game this evening. It suggests multiple hours of showers and thunderstorms.
If I take everything into account, it's truly a 50% chance of showers and thunderstorms in Champaign, between 6PM and midnight. But if I were to hedge on one side, I'd say the chances are a bit greater than 50%. The Central Illinois National Weather Service office has a 30% chance beginning at 5PM. I can say it's about a 100% chance for much of Western and Northern Illinois -- so again, the question is how much that precipitation will hold together as it moves into East-Central IL later today/tonight.
I'm not certain if I'll have a chance to update later, but if I do, I will.