FWIW, there’s a power plant on that lake so the temperature doesn’t vary as much by weather as you think. Having said that, most years it’s wetsuit legal(as others have mentioned).
I just posted some info under another topic but just to let you know my assessment of the bike course. I rode it this weekend. It is ugly this year. Lots of cracks and crevices, some that will swallow an entire front wheel. The lack of rain has really destroyed the roads on the first half of the course. Be careful and keep your head up. I hope the officials are lenient about penalties for riding on the right because in some cases you just can’t.
Also, there is a short 100yd section of road that is being rebuilt and as of this weekend was still just dirt. It narrows down to one lane too. I don’t know what the plans are for race day but I hope it is well marked so people don’t get caught going 25mph through there.