I actually have a function to validate the input but I see now that Weather Underground also does -9999.00 (I was checking for -999). https://github.com/OpenSprinkler/OpenSprinkler-Weather/blob/master/routes/weather.js#L566
I will update the code to correctly address this ASAP.
Thank you
Update: I do attempt to convert negative values to 0 as it stands here: https://github.com/OpenSprinkler/OpenSprinkler-Weather/blob/master/routes/weather.js#L85 but testing shows it doesn’t work.
Update 2: This should be fixed now and was due to type casting the value to boolean which makes any number true. Commit: https://github.com/OpenSprinkler/OpenSprinkler-Weather/commit/58e5db163c039798790e03d30ee88b791709e85c