I am racing in a local tri on the 4th. I don't believe it is a US Tri event and I think wetsuits are allowed. It has been very hot and water temps are pretty warm. I have a full QR wetsuit and am not the strongest swimmer. The wetsuit helps me a fair amount. The swim is 1/2 mile. How warm is too warm to swim in the wetsuit? I don't want to get over-heated, but I also don't want to swim without it if I don't have to. Any thoughts?

How warm are you talking
How warm are you talking about? I swim in mine all the time and have never had a problem.
USAT states the following: *
USAT states the following:
* USAT rules state that competitors may wear wetsuits if the water temperature is 78 degrees or lower.
* USAT rules also state that if the water temperature is between 78.1 - 83.9 degrees, competitors may wear wetsuits but will not be eligible for awards.
*If the water temperature is 84 degrees or above, participants may not wear wetsuit.
Since, you stated this is not a USAT event, the above doesn't really matter. But those guidelines are still there for safety reasons. In my opinion, I would probably draw the line at 80 for the water temp on a 1/2 mile swim. For a longer swim I would stick with the 78 standard.
It's all a personal comfort
It's all a personal comfort issue with these conditions. Personally, I'd rather come out of the water a bit chilled (although it's never happened) than realize 500m in, "Dang, I'm hot." You can't take it off. You can't roll anything up or unzip. You could skip the stupid swim cap. That helps me tremendously. If I think the refs are paying too much attention to swim caps, I'll at least start with it then strip it off about 50m in, tuck it into my collar. Too hot.
If you get in the water the day before the race, it will feel much cooler than the day of the race. On race morning, you'll be thinking of many other things to even notice. A good "pee in the pants" will also warm you up for a sec. You'll dry off on the bike and warm up for certain on the run. You could also apply the Sierra Madre philosophy: "Wetsuit? WETSUIT?! Ha! We don't need no stinkin' wetsuit!"
I was going to wear it until
I was going to wear it until I read "Wetsuit? WETSUIT?! Ha! We don't need no stinkin' wetsuit!" One of the best swims of my (short) triathlon career. Sure made for a lightning fast transition too. Thanks to all for the advice. Temps were in the "mid-seventies" according to the race director, and I was glad to be without. Great race overall.
I want to know from you,
I want to know from you, What should be the normal temp of wetsuit?
Anything over about 25
Anything over about 25 degrees and you will probably become a bit warm in the wetsuit.