Rain Delay is a manual control – it stops the controller from watering for a specified amount of time. Rain Sensor requires installing an external rain sensor, and it stops the controller from watering when the sensor detects rain. Weather-based Adjustment makes use of real-time data at your nearby weather stations, and automatically calculates a watering percentage that combines not only information about rain but also temperature and humidity. Although these three features are conceptually related, they are independent. See the chart below:


Trigger

Action

Delay Time

Notes

Rain sensor

Stations (except those that ignore rain) will stop watering when the sensor reports rain.
Rain sensor has a built-in mechanical delay, adjustable by opening/closing evaporation vents on the sensor.
Stations that are stopped, or scheduled to run during the delay time will NOT restart or resume after the delay time is over.

Change
Rain Delay

Manual. Stations (except those that ignore rain) will stop watering during the specified rain delay time.
Specified by the user.

Weather-based Adjustment

Water time is scaled by a watering percentage value (0% to 250%), updated every 15 minutes.
No explicit delay time. Water time may decrease (<100%) or increase (>100%) based on weather.
Accuracy depends on the proximity of your closest weather station.