They will be fine, just drink more.
Where I grow outdoors in summer, we get 7-10 days or more of 100+ days in a row, multiple times each season, and as long as they are kept properly hydrated, there are never any problems, be they 2 day old seedlings or at point of harvest. They are in full sun, all day, every day.
Make sure there is good air circulation and they will be fine. If you are really concerned, you could move your light further away, but I don't see a real need to do so, and I would not be increasing humidity beyond 40-45%, the high temps AND high humidity could lead to fungal/mould problems real quick.
Hot and dry is preferable to hot and moist, when it comes to cannabis.
P.S. - 18/6 will do more for your yields and is optimum for autos.
Hope this helps,...........
Organoman.