If it is just for a couple of days because of the weather (it's raining here now and humidity is really high also) you can just average it over time. If it is really high where you are in general, you may need to put a dehumidifier in the room to get the humidity down low enough. The humidity doesn't have to be at an exact number every second, you can let it average out over the three weeks. Weigh your eggs or keep track of air cells to see which way the humidity needs to go. Sometimes when you add eggs to an incubator the humidity seems to run high because of the eggs for a day or two. Or if the incubator has not been running long, same thing, the styrofoam ones are bad at that, especially if you washed or cleaned them in the last day or two.
Too high for extended periods of time in my experience.
Unless your weather is particularly humid at the moment try reducing the surface area (not the depth) of the water you ware using in your incubator. That should lower the humidity. You may also try increasing the air flow, but don't go all out with that as too much can be as bad as too little.