The only temperature that matters in a grow room is that of the plant's leaf surface.
Thermometers attached to the wall are irrelevant since temperatures under hot grow lights can soar well above ambient room levels.
Growers new to indoor cultivation can be shocked at how much heat is generated from a typical HPS grow light. While very bright, about half of the energy generated from these grow lights is in the form of heat.
Keeping a proper distance between the bulb and your plants will help ensure that you avoid heat stress on your crop. Adequate airflow goes a long way towards meeting this objective too.
Not sure if your lamps are too intense? Try the "hand test" or the "face test." Place the back of your hand at the plant level and expose it to the light, or better yet, stick your face down there.
If it's uncomfortable for you, how do you think your plants feel?
Make sure to keep your plant temperatures under 85 degrees F (about 30 degrees C), and they'll be fine.