Well, I have a number of trees that broke dormancy very early and have put on a lot of new growth and figs while they were still indoors. During that time I tried to give them as much natural light as possible. I also did not put them outside until late in May (partly because the weather has been horrible, partly because I have lots of Ambrosia beetles flying around looking for tasty trees to bore into, and I didn't want to risk any of these trees.)
So, it definitely isn't a case of them getting cold-damaged.
In this case I don't think the sunburn is because of high temps. I think it is because, like the leaves, they got accustomed to a certain light level while growing indoors and then got put out into the sun abruptly. None of the trees were put in complete shade, and some of them got more sun than others. I have some trees grouped together where there is no sign of sunburn on some, but some leaf sunburn on others. I chalk that up to the different amounts of strong, direct sunlight they got while inside the house.
So, I'm really speculating that some of the figs on at least one tree were a bit on the tender side, not having gotten enough sun inside. Then, when they got moved outside, they got more than they were used to.
A couple of figs on one tree got dropped. They were some of the smaller figs on that particular tree. One dropped within a day of being moved outside, but the others dropped after about 5 days. Again, it may also be because of the general shock/trauma of being moved, temperature cycles, rainstorms, etc. within the last week. I believe some leaves on that tree are also a bit sunburned.
Jim