I haven’t seen OS v3 but assume the interface is basically the same as my v2.1…
On your OS base web page there should be a “block of little blocks” in the lower right corner.
Click that and you should get a menu, one entry of which should be “Change Rain Delay”, select that and you should be presented with a dialog that you can enter a manual rain delay in days/hours that will disable the running of programs during that defined period…
HTH