I heard if you put foil on your windows it will keep it cooler , but won't it catch fire with all the heat?
Aluminum foil will not burnAluminum is a good transferer of heatYou would be better served if you put a shiny or mirror like coating on the outsides of the windows.
Or try Bitter AppleIt comes in a spray sold at most pet storesIt tastes horrible so most animals will avoid it but its harmless.