Why has the WeatherUnderground API stopped working? No access to the forecast.

Welcome.

Does anyone know anything why the WeatherUnderground API hasn't worked for two days?
Have they changed something or is the free forecast no longer available?

Generally the free Weather Underground API was supposed to run until the end of 2018, maybe you missed the email from early November where they explained the situation. Apparently things dragged on a bit and it worked a bit longer, just until Tuesday. I myself have a mini weather station on my ESP getting data from there and it stopped working on Tuesday evening. You'll have to look for more info on their website/forum.

And is there any alternative?
Generally I just need the weather forecast and the phase of the moon.

Unfortunately I have no idea, I made my station from a ready-made one found on the web.

Edit: see this https://openweathermap.org

I thought there was an option to buy some kind of API and Wunderground would still work for me but I see it's not that simple.
I also find it strange that I can't log in to the Weatherunderground website or even reset my password.
Will have to switch to Openweathermap. I have a ready-made station that works with this service but I need to extract the bare data.
And again, several hours of tinkering....

Unless someone knows a way to stay with the current Wunderground API, at appropriate charges of course?