They're not summer growers. However, they're not really winter growers either. They are pretty opportunistic and pretty much prepared to grow year round, whenever it isn't too cold, isn't too hot, etc.
Your's looks well stacked up, and what is it doing down the side? Making a pup? Or just very old leaves. Nothing for a week or two, then water lightly every now and then. Try to keep the new leaves fat, but the old leaves thirsty. The old leaves should dry out over the summer until you just have that nice red pair left by autumn. Then another set will grow.
They're tough and tolerant of sun and heat, but don't want to be soaking wet in high heat. Through the summer, just water lightly enough that the soil is dry in a day or so, but do it often enough that the newest leaves don't shrivel up. This is called "spraying" in mesemb parlance. You can spray or squirt or splash or whatever you like, but don't soak it in a bucket when its 110F! The danger time seems to be when night temperatures stay above 15C, give or take.