It all depends where you measure......I started the first grow at the of May, and we have had a warm summer here, not a scorcher but warm, and since I refuse to consider air-con because of power consumption, the temps is totally depending on the ambient temps. If I had total climate control, I would aim for 28-29 C at 1 M, and a little higher at canopy level.......but that's just me!
Remember the more the plants transpire, which is a combination of Temperature and Humidity, the more nute enriched water they will pump through the system. When the temps went up to 38-39 C at some periods when there was a bit of a heat wave, I was watching closely, but if anything, they grew even better/faster......maybe just a perception.