There’s a tutorial to use the RSS feed from NOAA to get weather alerts: NOAA Weather alerts using RSS feed (US only)
And I started messing with the NOAA/NWS weather API at: Which weather binding to use
The problem I ran into was parsing out the forecast and calculating the predicted precipitation for the next 24 hours. They have an indeterminate number of elements that cover non-fixed time periods which required more XML parsing and processing than was easy to do in Rules DSL. But I think everything else worked.
It should get someone started. If they want the forecast though I’d recommend using Jython or JavaScript instead of Rules DSL to parse and process the XML to extract and calculate the 24 hour (or longer) precipitation. Everything else can be pulled using XPath.
I’ve not looked at this in years but I think there might be a JSON endpoint now in which case JSONPATH would work.
Personally, all I care about is current temp, current humidity, and current cloudiness. OWM is accurate enough for that so I take the easy path.