I've been waiting for cooler weather to divide some hosta, salvia, daisies, etc. Do you think it is still too hot?
no, i don't think so, esp with the good rains we've been having. If you can hack it and can baby the plants for a few weeks and keep them watered if it doesn't rain, i'd say go for it.
Yes, you should be able to begin your division now of those plants and do give them all haircuts so the energy of the new transplants does not go to producing new growth but good root systems. Keeping them watered is primary in the first few weeks. Soon you will begin to see new growth again before winter sets in.