The older leaves will always be a darker green and the newer growth will always be lighter. This is how mother nature works her miracle plants. Anyways with really high temps you get burnt plants and stunted growth. Just make sure your temps don't get over 85 then your really testing your watters. The humidity is fine the best way is wet towels like I told you previously. JUST WATCH THE TEMPS, do you have a fan on them???? Fans are very important, because they build tough strong stems for budding and keeping the canopy of the plants cooler from the lights