In general if the air temperature outside is 32 °C when indoors it is 24 °C then opening the windows will make the house warmer.
However, opening one window at one side of the house and one on the other, and keeping doors between them open, will create an air flow - a draught. Science says that an increase in speed will cause a drop in pressure and this will also cause a drop in temperature (combined gas laws). It is how fans work.
Keeping blinds and curtains part closed work well, especially on the sunny side. We all know that sitting next to a sunny window makes us boiling hot. Blinds etc. being good insulators, stop the sun's rays and some of the heat.
Go to any hot country and all the windows have at least nets or blinds.