Thanks for noticing the changes. I am preparing a post to announce the new weather service and the key changes (we are still trying to fix a few minor things so I am holding on to the announcement until those are ironed out). To quickly summarize without making this post an announcement itself:
1. The biggest change is that ETo is now available as a third weather adjustment option. This is more sophisticated than Zimmerman algorithm and it’s a widely used industry standard. We have updated our support article: https://openthings.freshdesk.com/support/solutions/articles/5000823370-using-weather-adjustments
to explain it. In particular, the baselineETo value must be set properly when you choose this method.
2. The weather code now has support for multiple weather providers: DS, OWM, WU, and local. Our own server, weather.opensprinkler.com has switched to use DS as the default provider, and we’ve moved away from OWM because their data quality is not great.
3. WU support has been added back, if you have a WU API key and selects a PWS location. However, you won’t see it in the UI yet because it is only enabled for firmware 2.1.9 or above which has not been released yet. This is due to the way WU API key is stored, which unfortunately does not fit in firmware 2.1.8.
Officially WU has pulled the plug, but behind the scenes you can still apply for a WU API key, even if you don’t own a physical PWS device. See our updated support article: https://openthings.freshdesk.com/support/solutions/articles/5000017485-getting-a-weather-underground-wu-api-key
This is very much gray area. Given their recent fiasco, I won’t be surprised if they suddenly remove the support all together, so use WU at your own risk.
4. You have correctly noticed that ETo is not available with WU, mainly because ETo requires an ‘average solar radiation’ parameter. WU only gives ‘maximum solar radiation’ and does not provide cloud coverage data, so we can’t estimate average solar radiation using WU.
Regarding Local: I am not entirely sure. Pete or Matt will be able to answer this question.