How to add OpenWeatherMap to dashboard?

I'm trying to use openweathermap map 1.0 (which is included in the free subscription) in a dashboard tile.

Image URL I am using is

https://tile.openweathermap.org/map/precipitation_new/10/193/410.png?appid=[my api key]

I can't get this image to work either in the browser (I just get a dark gray box) or in the dashboard. I think I followed the URL format correctly, the example they give is:
https://tile.openweathermap.org/map/{layer}/{z}/{x}/{y}.png?appid={api_key}

where {z} = zoom level, {x} = map x tile coordinate, {y} = map y tile coordinate

Anyone else been able to get this working?