how to best check temp

my question is, in a small cabinet grow (30x30ish), what is the proper way to check the temp? if i put my thermometer under the lights, i get a greenhouse effect from the light; my temps read about 35c/95f. but if i put the thermometer in the upper part of the cabinet so that the meter is above the light, i get 27c/86f.

i have an exhaust fan in the right back corner, vent holes in the bottom front corner. the meter is center right wall 2/3 up.

seems that the air temp should be the important thing, but hey, waddaigno?

I use an indoor outdoor thermometer and kepp the outdoor part at bud height so i know the temps at bud level and i put the indoor part on the wall at light height. Also i hope you are using some co2 because your temps are pretty high you should try to keep around 77 degrees farenheit day and no lower than 10 degrees less at night, i hope this helps