Soil moisture shows zero. Watered landscape to field capacity more than a week ago, but the temperatures have been below freezing. ET has been exceedingly low. Rachio, do you have a reply to this? I am not planning on watering, but i do not understand how you are calculating the soil moisture.
Well post your weather station Id at the very least so that they have the ability to verify the integrity of the weather data.
The formula for this is well documented just follow the rabbit hole http://blog.rachio.com/2015/07/what-is-evapotranspiration/
KPWA is the NOAA station. I listed it in another comment.