The particular weather station is not the problem. Wunderground is messing up during the interval where California (my location) is still in one day, and the wunderground servers are already in the next day. I am simply asking to make the weather script more robust so that negative precip values are turned into 0. That doesn’t fix wunderground, but makes OS more robust in the face of such issues and helps keep things watered properly. Sine negative precip cannot exist, this fix can do no harm.