Where are you located Dan ? You certainly need a local PWS to give you rain data to get it to skip the raining days.
However, I still do not fully know what happens with the general weather data (when using the Flex-Daily mode). Initially, when I setup my system, it calculated times for zones. However, a month or so later, I went to start over again but it would not auto calculate things for me. I had to set up my location as a place in Texas, setup my fictional zones, and then set my location and PWS to Spain.
I had a lot of interaction with Rachio support who basically said that it wasn’t fully supported, but I am still unclear as to how it’s working with my local PWS and whether it only looks at the rain, or whether it’s also looking at the other data - or to what extent it’s using the other data.