Here is my irrigation app
This little app uses a weather driver to collect data on recent rainfall and predictions of further rainfall
Then you can set 'weighting' to these results and a threshold to decide whether to turn on a switch or not.
I use this to tell me to water my garden if there has not been enough rain in the past and it doesn't look likely that there will be enough soon.
You could, of course just use it to open a valve to directly water the garden if you have that facility
I use it with my 'Weewx/Apixu' driver so I can use my own PWS to collect accurate data
But.. if you have a current Weather Underground API key you could use my WU driver
You can find both of them here:
https://github.com/CobraVmax/Hubitat/tree/master/Drivers/Weather
You can use almost any weather driver providing it sends the following attributes:
"precip_today"
"rainTomorrow"
"rainDayAfterTomorrow"
OK...
You can find the app here:
https://github.com/CobraVmax/Hubitat/tree/master/Apps/Irrigation%20Switch
Please let me know if it doesn't work for you or you find a bug
As always, I'm happy to take suggestions on how to make this app better/more useful
All my apps now provide remote version checking - announcing in the app and logs if an update is available
Andy