Small marijuana plants

A question from a fellow grower:

A query if I may? My plants were grown under what I consider fairly
optimum conditions. Nursed, cuddled and loved (outdoors). Plenty of
sunshine in what is considered to be good climate, hot days, often
around 30 to 35 degrees selsius. Now ready for harvest. Plenty of small
heads but not one plant grew more than 16 inches tall. Not a complaint
but I would appreciate some input from you. I’m looking forward to next

I’m growing outside to, and mine are smaller than I think they should be.
I think it’s the high temp, 30 =86 f. That is about where I’m at also.