I blogged about this last year, but I'm still puzzled!
It rained here for nearly 24 hours (as I type, it may have ended... or perhaps it's just a pause) so the ground is pretty soaked. My Big Girl has either learned to count or tell time, because the sprinkler system goes off after midnight, then around 3am, and then just before 5am, which is when she wakes me for breakfast.
This morning, as she was nudging me to get up and feed The Herd, the sprinklers went off. As it was pouring rain. As if the little patch of lawn in front of the building hadn't gotten enough water.
If the system can be turned off (at the end of the season, or during a drought), surely it can have a sensor that says it's already wet out?