Maybe it's just that I'm used to the heat. Our summer temps are usually in that 30-40C range and I rarely wear shorts. (Don't want to blind anybody with the glare off the pasty white legs ) It doesn't bother me to wear the kilt and hose in those temps. I find it cooler than long pants. As for the shirt, I'll wear anything from a T-shirt to a polo or a long-sleeved shirt with the sleeves rolled up, depending on the occasion.

RiverKilt has posted plenty of pictures of him wearing sandals with his kilts.