Whilst opening the windows if the temperature is warmer outside than inside can let in warmer air heating up your home. 

To make the most of the cooler temperatures be sure to open a window (if it’s safe to do so), at night or as soon as temperatures start to drop in the evening. 

This will let in that cool evening breeze and hopefully banish uncomfortably hot nights. 

Temperatures are often cool in the early mornings so leaving windows during this time can further help to cool your home but remember to close them as soon as temperatures start to rise.