Years ago I developed a watchOS app Slippery Weather (Liukkaat kadut in Finnish) displaying pedestrian slippery weather alerts to users. I sold it at the App Store, and later lowered the price to zero, offering it as a free app.
However, I didn’t have time to maintain it, so I took it off the App Store recently. That was a good decision, since I’ve now learned that the service providing the alerts API has ceased to operate.
The service got the slippery weather condition alerts from the participating cities (road maintenance folks) in Finland. It seems that the cities have switched to using Finnish Meteorological Institute (FMI) weather model based alerts instead.
I do have a prototype watchOS app using Apple Weather service local weather data. The prototype attempts to predict slippery weather for the next 12-24 hours, based on recent and forecasted temperature, precipitation and humidity. But haven’t had time to work on that either. Doesn’t work so reliably that I would want to publish the app.
Learned a lot while developing the app though. Everything lasts for their allotted time, nothing is permanent.