I haven't tried a wrap, but Jet Hot coating dropped the header tube temp from about 400F to 300. I didn't experiment enough to know if it would change the engine temp, but it should help some.
These do get hot at idle, but won't overheat unless something's wrong. If they did there would have been a big piss up with Honda a long time ago. And humidity makes a person feel hotter but doesn't make an engine hotter so that 95% thing Fur mentioned is irrelevant. Fizzy brought up some things worth checking. Also, the gauge could be lying so checking the engine temp with something else would be a good idea. I use an infrared thermometer and check the thermostat housing to verify temps.