I use Gnome Weather Report, an applet that shows the local temperature and weather conditions on my desktop. For the last few days, it’s been showing something really weird: 
. It’s nothing like -17°C here; it’s nearer 0°C, according to Environment Canada.
Things become clearer when you change the view to Fahrenheit view: 
. It’s clear that the sensor or protocol is broken, but is being mis-interpreted as a zero signal.
As an avid RISKS reader, I know that confusing zero and null values is pretty much unforgivable. I’ve wired up enough 4-20mA current loop instruments to know that having a zero-value signal being the same as a no signal value is bad.
But there’s no real risk here. I mean, I could always go outside and find that it’s not 17°C. You don’t need a weatherman, as Bob said.