The plants may abort the blooms if it is too hot. You can tell if it necessary to water by inserting a finger into the soil to a depth of 4". If it feels almost dry or dry, I would water them.

If you do that daily for 2-3 weeks and note on a wall calendar when you water, this will give you an average of how often to water. So if the notes suggest that you were watering every 3 days, you can set the sprinkler to water every 3 days. Re-check again if the temperatures go up/down by 10-15 degrees and stay there. Watering daily sounds like too much and could cause root rot (if the roots stay in wet soil for long periods of time).

As for when to water, it is best to water early in the morning. You can water the soil and skip watering the blooms and the leaves. That just promotes fungal infections like powdery mildew, etc.

Since ES is a rebloomer, I would deadhead the browned out blooms so new bloomage will occur.

Thanks for the feedback, I appreciate all your tips. Great suggestion to deadhead all the brown ones, thanks again!