My First Grow! IncredibleBulk & StarDawg

This is a classic sign of heat stress my friend , its good that you notice it early on like that so you can correct the problem now instead of when its too late . Now that we have established that its heat stress , there are a few things that you can do to correct this , you can get a bigger intake fan combined with exhaust this will circulate the air faster around your room making it cooler over all , you can get a portable A/C these work wonders in grows :D :D another option you could try is lifting your lights higher if you can or getting a cool tube to vent the heat of your light straight out your room . I personally dont like having my temps over 27C during the day and no lower then 19C during the night . I hope this helps shed some light onto your problem as well as giving you various options you can try to lower the risk of heat stresses . Over all your plants look great and you're on your way to a great harvest !