Temperature to high

Hey I am currently running a closet grow 1m squared with inlet and exhaust fans under a 600w HPS light, I have a 9 inch desk fan to circulate air but the temp is sitting around 90F!! How could I reduce heat?
The closet is about 7ft tall inside. I have my exhaust fan high up and everything else low at the moment as the plants are barley past sprouting stage. I an wondering if the cerculating fan is to much and not allowing heat to rise but just nit sure. Any tips would be great.

What size exhaust fan and how many cfm/cmh is it rated,is it an inline centrifugal (vortex,canfan,etc.,or a squirrel cage dayton,panasonic whisper)?

What are the temps of the room the closet draws it's intake air from?

Where are you exhausting to...the room the closet is in,out a window,the attic,another room?

Is your intake twice the area of your exhaust?

600w HPS work best on a 6 inch dia vent, that said keep the air moving ensure the outlet is up high, the inlet low and passive, that is no fan inlet

Yes 600w HID's work best with 6" and up inline centrifugal exhaust fans Vostok but....

If OP's ambient/intake temps are too high to begin with then it won't matter,and that is why I asked those questions as there are many variables and first in order to truly help the OP we need to know all variables of his/her setup rather than just saying x or y fan will do the trick.

I had/have the same issue. I put a 18" round oscillating fan to blow away the hot pocket of air between the canopy and the xxxl cool tube hood. I have the SAME heat issue even if im running my a/c. I run 73* a/c on, and 84* under hoods with or w/o the ac on. its a hot posket of air that's trapped under the hoods. and please don't tell me I need more exhaust as I run a monster carbon scrubber with one 750cfm fan AND and 440 cfm fan, an 8" 440cfm intake fan on speed controller and my a/c runs constant for 12hrs.
and im not a new grower.