Temp, humidity fluctuation??

Whats up rollitup? First post/grow. Have 3 OG Kush growing under a 600w HPS in a 3x5x7 closet, 23rd day of 12/12, feeding full line of fox farm nutes and molasses every other watering. The plants seem to be very healthy. My question/concern is when the light is on the temps are 86f-89f which is pretty high I know, and my RH is 30%-35% which ive read is somewhat ideal. When the light is off Im at 68f-71f and 45%-50%. What effects would this fluctation have at harvest on things such as yield and quality?
Any help and or feedback on this would be greatly appreciated... Thanks in advance!

do you keep the fans going during the dark?

During light I have a 20" fan blowing into the closet for circulation along with central air ducting running directly into the closet, 6" duct fan sucking air out into the attic, the 20" is not blowing in because I cover the closet with a blackout curtain during dark but central and exhaust is still running.

So you dont have an oscilating fan going but the exhaust is? i'd get a fan to put in there if you dont.

Correct, I do not have intake air going into the closet during the dark period. By doing this it should keep my dark period humidity lower right?

it would provide an even airflow so your plants dont have pockets of little air movement where mold and such things can and usually will develop. I've had bud rot before and it really sucks.

You know, you can wire your thermostat and hygrometer (humidistat) into your inline duct fan (is it inline?) so that your air circulation circuit kicks on when your humidity goes over, say 50% and/or your temp goes over 70F. Remember it's relative humidity, so the warmer your room is, the more humid a given percentage is and the more difficult that humidity is on the plant (the harder it is for the plant to transpire Oxygen/CO2).

Remember the doubling rule: Every increase 20 Degrees F. your air can hold twice as much water and will if it's available. I'm semi-plagerizing from a Cervantes' chart now. For an 800 ft grow room, at 70F it can hold 14oz of H2O. At 90F double it: can hold 28oz H2O. 50% humidity means 7oz water in the first examble but 14oz H2O in the second: double. If you're in a humid climate your plants are literally drowning for life providing respiratory gasses. The stoma are humidified shut and they can't transpire CO2 or O2.

Consider the humidistat. It's relatively inexpensive and all it does is turn on your fan - whatever fan it's wired to. If you are having troubles.

Most garden's on a small scale or large have a spike at some point during the day,I like the humidity to be around 50% al the way through thwe grow.Do the plant's look ok if so don't worry about it the temp's are not that bad at all have a fan blowing up at the light if possible this will lower the heat but like i said go on what the plants look like if there a good coulour then there is no prob peace..........tyke...........................................

Absolutely, 50% works great all the way, seed to harvest. You can get more picky with the various stages of growth, but if this is one of your first grows, get it to 50% and keep her there. If you want:

Clones: 80%-95%
Seedlins/Vegetative: 60%-75%
Flowering: 40%-60%

but for seed to harvest, 50% is the magic number. If you clone, get more particular.

Tyke1973 is right on his second point as well. Your leaves are your best barometer. If they look good - you're doing good