Hi - Floridian here to say weather forecasts can and will change by the hour! Which doesn’t help with packing, I know. So here’s my advice:
Odds are slim for a truly cold front: bring some lightweight layers if you chill easily, but no need to go full arctic blast.
You can’t do anything about lightning: if it’s present, we won’t run. Don’t waste energy worrying about it. rD will make that call.
Rain… is a real possibility. You won’t really know how much or at what time until a couple hours before race time, at best. Pack ponchos, baggies for phones, newspaper to stuff wet shoes (speeds drying time), and plan to embrace the suck. It’s just water: it won’t hurt you!
If you don’t need any of that, great - but you’ll be glad to have it if it is needed.