It is very difficult to stay dry in hot and humid conditions. But do you really want to?
In 100% humidity, sweat can't evaporate unless your body increases the temperature of the air, raising the dew point. This will be impossible if the air temperature is the same or higher than your skin temperature. At these temperatures it will be virtually impossible to avoid sweating and you will soon be drenched.
It is more likely that temperatures will be below skin temperature allowing some evaporation to occur, though the effect of high humidity can cause danger from heat exhaustion at relatively moderate conditions if you are working hard. This table indicates the heat stress due to humidity and temperature.
The best option is to reduce insulation and you may consider it more comfortable to get wet from the rain than overheat - hyperthermia is as serious as hypothermia. Water (sweat or rain) conducts heat very effectively. By using the rain to keep you cool you are less likely to dehydrate.
By allowing your legs to get wet FurTech jackets can be used in very hot / wet conditions. Just add the trousers over wet legs if you begin to feel cool.