Too Much Heat?

This is my first grow, and I'm using CFL for Veg and going to be using HPS for flower.

A few days ago, I noticed that some of the leaves were starting to yellow. Going through some of the symptoms here I thought maybe the closet was too warm. So I opened the door and the temperature has been hovering around 75 - 80 (was about 85 prior) since then.

Do you think this is heat or perhaps something else I should be more concerned about?

How often do you water?

Jesus. me too. Im in the loft during summer and its unreal! Embarrisingly high!
Im gonna have to move down i think!!
The yellowing looks similar to mine! Mine are def due to heat!
Check it aint nitrogen deff.
safe

im a first time grower also man, therefore not very experienced but id say you need bigger pots for those plants, transplant asap, are u adding any type of fertilizer? also a little raise in the lights could help the heat problem and point the fan directly to the tops

Your plants aren't root bound. There's no need to transplant.

Sorry, I thought I had subscribed to be notified when there were posts, but I must have made a mistake.

Watering: I have a moisture sensor and water when it reads below a 5 at root level. That's ended up being about daily about 1 quart between 4 plants.

Roots: I agree about transplanting; the roots are starting to come through the drain holes at the bottom of pots.

Air: Fan blowing 24x7 as well as light on 24x7...

Temperature: The temperature in there has been around 75 F today, high of 85F in the last few weeks...

The good news is the yellowing has not increased. I tried adding a 10-15-10 fert yesterday, and I put 2-3 drops in for the quart of water (it suggested 7) before mixing it up with filtered water.

Thanks for the suggestions, I'll check on it tomorrow morning and post an update.