While this is only available in the US at the moment, this could be something to keep and eye on if the planned European update emerges.
The application is an add-on for TPE (The Photographer’s Ephemeris, well worth a look on it's own if you haven't done so already) which analyses items like topography, cloud height and type, as well as gap light to predict how good sunsets are likely to be.
While applications like this are never going to be 100% accurate it's another tool that could be useful to landscape photographers wishing to plan ahead.