Back in July 2015 @franz said
" The calendar itself is just a prediction, using forecasted data. One hour before the flex schedule runs we get the current forecast, look at the current soil moisture level, and decide if we need to water. If it is on the calendar, it doesn't necessarily mean that a watering will take place."
It's in this thread.
So it will recheck everything before it wants to water again. If you look at the details, you will be able too see the recorded precip on past days from your weather station, and the predicted amounts.