It's not down,it start charging for its service: https://wxdata.com/pricing
They were already charging, but a sub-set of the Weather.com data had always been free (or at least we could get if for free until now).
The problem is that their pricing is absolutely over-the-top outrageous! For instance, they want $620 per month for a maximum of 20,000 requests *per day* (not even per hour). Free applications like Nexus and ObjectDock have many times that number of users and the weather info is updated *per hour*, not per day. For something like 500,000 daily queries Weather.com basically wants $3,000 USD *per month* - I think with pricing like that they are thinking more of websites, not always-on widgets, especially with many of the latter being free.
Is it any wonder SD decided (IMO) to stop paying Accuweather for the info used by the OD weather widget? It just didn't make financial sense anymore!
For comparison, Winstep pays MaxMind for the Geo location services used in both the web site and the applications, but that amounts to something much more reasonable like $50 USD every 2 months or so (and, of course, it is also less queries since they are then cached locally, but still). Now THAT is reasonable pricing for these type of widgets/applications.
Keep in mind that these days, for less than $150 USD per month you can even rent from any reputable NOC a fully loaded bare metal server with 20TB of dedicated monthly bandwidth on a 1Gbps port.