UIL WILL be happening this Saturday. Yes, it's stormy, but Monday is looking like it'll be more stormy than Saturday. Right now, based on what I've heard, the plan is for bands to go nonstop (as nonstop as weather allows) to get all performances in. Once all performances are completed, if it looks like finals performances will run past midnight, state advancement will depend on prelim scores.
This information has been communicated to me by my band directors.