It's the same here Lyn. It really doesn't cool off at all until a couple hours after sundown. But it appears (for here anyway) that as long as the sun isn't baking them, the semps are okay after watering for the couple hours between sundown and cooldown. Like Lynn said, I think it's all about experimentation and finding what works for your area.
Plus, I'm sure my neighbors already think I'm insane, so I really don't want to reinforce that with watering plants by flashlight at midnight.
