Which blinds for summer

Hi all. Our living room has a set of 6 windows with no blinds currently. Last year this was really hot during the summer.

We're currently considering some light filtering shades. Specifically the Morrison from hunter Douglass. I think the opacity rating was a 3.

Would light filtering shades make a big difference? Or would we need something more oapque closer to blackout?

Windows are about 6ft tall and range from 3.5-5ft wide