The higher the humidity, the less effective evaporation will be as a cooling method. For example, while the air is at 10% humidity, the swamp cooler can drop temperatures by up to 20 to 30 degrees, while at 50% humidity, the swamp cooler can drop temperatures by about 10 degrees.Click to see full answer. Besides, at what dew point do evaporative coolers stop working?If you want to gauge a cooler’s efficiency in terms of dew point, just keep in mind that, in general, a dew point in excess of 55 is generally a swamp cooler humidity limit. what should the humidity be in a swamp cooler? 50% In this way, do evaporative air coolers work in high humidity? As a result of their cooling process, evaporative coolers also add moisture and humidity to the air. While this is beneficial in dry climates, it also means that evaporative coolers are not as effective in more humid climates. Typically, evaporative coolers work best in areas in areas that are very dry, as well as hot.How do you use evaporative cooling in humid weather?All you have to do is open a window to let in dry air from outside and allow the moist air from inside to cycle out of the room. You can open a door too. This will create a cross-draft in the room and allow moisture to escape, keeping the room’s atmosphere dry enough to allow the swamp cooler to keep creating cold air.