Be backed up into a shadow with something behind ya to breakup your outline. I can't recommend enough 3D Leafy suits. North Mountain Gear make a nice inexpensive one you can find on Amazon.
AllPredatorCalls.com sells the Kill Suit Mesh Ghillie Suit for hot weather hunts they're Awesome for not dying in the heat!
If you get the Mesh ghillie suit... don't get the combo jacket+pants.. just ge tthe SAPR suit model which just hangs a little lower like down to the knee. That's all you need. With the pants... when hiking to next set they pick up bunch burrs like crazy. PITA.
I'll include some picks to show an example of the two suits. And also 3D Leafy Boonie hat, and Mesh Facemask. My fac in the Mesh facemask from Natural Gear. It blends in with lots of other gear very well.
With the leafy suits on, while standing, I've had yotes and bobcats looking right at me, and they don't recognize me as being a human or an animal for that matter.
This is the North Mountain Gear one. They come in two shades.. this one, and a more green/gray one.
this is the Kill Suit Mesh Ghillie Suit SAPR model. They have Desert and Woodland. The woodland is Green plus other colors. You'll see the pics on their site. If you can help it, you don't want to wear this Mesh Ghillie suit and then put your pack on yourself while wearing this, as it'll pull and tug at the mesh strips and that will cause the strips of them to possibly become unsewn and droop. And when that happens they can want to catch on your buttstock when bringing your rifle up to bear when seated.
Also I mention the Leafy Boonie hat and mesh facemask because that hat is nice and light and thin so your head doesn't cook. Same with the mesh facemask.
In Arid/Desert regions... this Killsuit Mesh Ghillie really makes you vanish! So if you're wearing either of them on a sit... and if the possibility of other Humans with rifles coming into the area in pursuit of animals exists. At the very least shove a Blaze Orange cap onto your pack like a visibility flag, sticking up so some retard doesn't point their rifle at you because they were never taught to NOT use a Rifle scope to scan the landscape.
Depending on the area, on how dang hot it is, it can be useful to bring along a blade with a serrated edge or some hand pruning shears so you can snip to remove branches from like a scrub oak or juniper to help you stuff yourself backed up into them partially to escape the hot sun sometimes.