It’s my time to shine, right?!
Y’all… it is WAY too early to make any decisions in regard to weather! My home forecast for 90 miles west of WDW has changed 18 times in the last 48 hours.

I have no faith in the forecast for this Saturday, two days from now, let alone several weeks from now. Go ahead and look - it’s not a bad way to pass the taper time! But please don’t think anything this far out is accurate.
Once again: January in FL means anything from 20º to 85º and can include bright sun, dangerous storms, and anything in between. We genuinely will not know anything definitive until maybe a few hours before race start each day. Please see just last year, when the half was unexpectedly cut short due to dangerous weather moving in.
So how the heck to you plan and pack?! You bring LAYERS and make decisions in real time. A few days out will give a good general view of what’s coming - i.e.: if we’re expecting a cold front to blow through in the next week or so. But cold fronts are fickle and can speed up, slow down, or refuse to descend to Central FL altogether. Which is why we MW vets issue a constant refrain of “plan for EVERY possible weather condition.” You can’t go wrong if you’ve got options!
ETA: one thing I think lots of folks miss when packing for winter FL trips that should be with you, regardless of forecast… SUNSCREEN. Just because the weather’s cooler than summer’s surface of the sun temps doesn’t mean the sun isn’t still stronger than pretty much anywhere else you’re coming from. I diligently apply SFP50 every run and am still tanning through that this time of year.