We have just pushed out a version of new weather script that switched to use OpenWeatherMap (OWM) API. Basically, if WeatherUnderground (WU) key is provided, the script will still use WU service, otherwise it automatically switches to use OWM data.
To use it, make sure your app is up to date (version 1.7.4), or if you access OpenSprinkler using a browser, open a private browsing window (or clear browser cache) to make sure it uses up-to-date scripts. Then go to Edit Options -> Weather and Sensor, you will see that WU key is removed there. Instead, it’s moved to Advanced section. For those who don’t have a WU key, you can simply leave WU key field empty, and in Weather and Sensor section, choose Zimmerman as weather algorithm. If you have a WU key, but want to test the new OWM service, simply delete the WU key, that will cause the weather script to use OWM data.