Nick, yes; if the software gets an error or otherwise cannot communicate with the weather underground server then it will default back to 100% of the scheduled run time.
I’m thinking I understand what you’re asking for. If you click on the individual cell in the WUnderground column then it will pop up a box that tells you the overall parameters that fed into that calculation. e.g. the temp, the humidity, etc. Correct? That touches a bunch of code (the core C code, the html web page, and the database table that holds the data), but it shouldn’t be too terribly difficult to do. Let me root around in the code and see what I come up with…
Of course you can always look a the actual program log in /var/log/sprinklers_pi and there should be an error message in there as well as the actual data you’re looking for. If there’s a successful connection, you should get a message that looks something like:
2013/07/27 12:43:42 Adjusting H(-27)T(56)R(-114):15
This states that we’re subtracting 27% for humidity, adding 56% for temp and subtracting 115% for rainfall, resulting in a duration that’s 15% of what’s scheduled. (100-27+56-114). If there was a connection failure or some other failure, there should be an associated message in the log.