[Limeygreen]

Could try mist lines (coarse) on the glazing outside, this helps drop temperatures a lot too.

[growinthehills]

I'm going to reiterate what a lot of people have already said...
They can hang in pretty high temps. We had highs above a hundred consistently. Days that were extremely hot. No more than checking on the greenhouse after noon. We watered well in the morning. We also used a thick layer of straw to keep the beds moisture content even through out and keep the soil cool. Outside temps were 100 degrees regularly and 110 wasn't uncommon for a week or more at a time.

The hoop house always felt cooler than outside though when it was hot. Roll up sides, one openable end and two decent greenhouse fans mounted up high on the other end. We also had a shade cloth for hot days that i pulled over during the hottest parts of the day. When we wanted it to the greenhouse was 10 deg F cooler than outside. This was for a 20' x 96' hoop.