The joy of the indoor/outdoor thermometer.
Get yourself a digital indoor /outdoor thermometer. It's not NETFLIX but it does make excellent viewing!
Knowing the temp outside and inside helps you activly manage your house. When it's hotter outside than in SHUTDOWN - windows, doors, curtains. This will keep your house cool.
Put the outside reciever somewhere it will never get hit by direct sun (the south-side of the building, under a window ledge is good. The inside reciever can be anywhere you like to look at it.
As soon as the outdoor temp is cooler than inside - turn off the cooling (if you'd cracked in the heat and turned on the AC), open everything up again and let the cooler air in. You can also turn on your extractor fans to help purge your house of hot air.
If you've got evaporative cooling, turn the mode to VENT and push that cool air through the house.
And watch the temperature decrease on your thermometer! Such fun ...sort of!