Take advantage of the cool air that floats around when the sun is setting. If your room temperature is more than what is outside, use this trick to cool down your house fast without an air conditioner!
Keep in mind that hot air rises and cool air falls downwards. Now pick a room or two you'd like to cool down fast.
Set up a window fan at a window upstairs (not in a room you're trying to cool down). Switch it so that it is sucking inside air outside. This causes hot air to be pulled outward.
Open up the windows in the one or two rooms you want to cool down fast. You can also open the porch door if it's located in a room you're trying to cool. Make sure all other windows and doors are shut (except for the window with the fan). This entire action causes hot air to pull outward while causing cool air to be forced into the house.