Every year around August, we get wrap around moisture from Arizona’s monsoon season and it makes our swamp cooler worthless. Higher humidity means less evaporation. The last few days we have had humidity rising at the end of the day and through the night to around 30%. Anywhere else, that might not be a big deal. Here the average tumidity is less than 15%, thus the evaporative cooler for the house. I guess this year the humidity is arriving early and making our house a bit stickier than we would like. At least we have fans to blow the air around.