Swamp coolers do not work when the Dewpoint gets 55 and above, then you feel the humidity in the house. We use ours until July then switch to a/c . What I like about the swamp cooler is, your windows have to be open and a door can stay open and the house is still cool. Right now Im in OHio with this humidity and feel hotter than when I am in Phoenix. When your old like me, you can only take off so many clothes before the clothing police might pick you up!! - Joan