I would think an extra gritty mix as Tarev suggests might be the antidote to the summer blues.
Our humidity averages about 70% with regular nighttime fog, and that plant is really common locally. It enjoys day long sun in our mild climate and will bonsai a bit in containers, more so if the container is too small or the plant has been in it too long. But if I had to make a short list of bulletproof, sun-loving container succulents in our climate, this would be on it, along with the jade. Especially drought tolerant, especially tolerant of neglect, especially tolerant of size constraints.As a landscape plant it goes on autopilot. If somebody here needed a succulent hedge and didn't mind doing a fair amount of pruning, I'd recommend this plant.
So maybe there's something about heat and humidity combined, especially with lots of rain. Our summers are cool, without a drop of rain. One would expect the times of heightened sensitivity to occur on the hottest days but especially when it does not cool down at night. Those would be times when the plant will theoretically be most refractory to excess water. That is when you might avoid watering and/or provide overhead protection to keep the plant out of the rain.
