For the record (maybe too late for you 
), although Netatmo have dropped integration to Weather Underground, there is a workaround that means my 2 x Rachio 2’s are still using data from my Netatmo weather stations.
To set up a link between Netatmo and WU, go to http://plus.meteoware.com/.
I seem to remember the MeteoWare link failed when I had 2 Netatmo weather stations on the same Netatmo account although this was subsequently resolved by creating 2 new Netatmo accounts and ensuring only one weather station is visible on each.