This is what Weathermodels.com says:
FAQS REGARDING THE USAGE OF ECMWF MAPS AND GRAPHICS
Recently, ECMWF has sent out a clarification of their Standard License Agreement to its customers, that some may have not understood in this way beforehand.
Weathermodels.com is about transparency and fairness, so we decided to make this Guideline page that informs our users exactly about the allowed usage of ECMWF maps and products, that they can buy through our subscriptions.
Weathermodels.com is a maximum charge customer of ECMWF data and does process this data to create maps and graphics (so-called Value-Added-Services (VAS)) for its customers.
ECMWF does regard any next tier of customers of their Licensees as so-called End users (that is you, if you have a subscription with us).
This holds true not only for weathermodels.com, but for any other outlet as well that provides ECMWF maps, charts and other ECMWF based Value-Added-Services.
That means, you don’t get any more rights to use ECMWF data if you choose to buy a subscription somewhere else. You would only get more usage rights of ECMWF data if you would be buying directly from ECMWF itself.
Can I share ECMWF model maps on the internet?
ECMWF generally prohibits End users(people that are not direct customers of ECMWF, meaning you) to broadcast their products or maps created based on their products - this includes Social Media.
However, ECMWF allows the unrestricted use, including commercial use, and sharing of their “WMO Essentials”, you can find these products here https://www.ecmwf.int/en/forecasts/datasets/wmo-essential. Thus, our weathermodels maps based on these parameters can be shared without restriction by ECWMF, but please make sure, you don’t exceed the maximum sharing for your weathermodels subscription type.
Can I share other model maps based on other weather models (ICON, GFS, etc.) from weathermodels.com on the internet?
Yes, you can.
Could weathermodels.com just pay more and buy a bigger license from ECMWF, so they could provide their customers the right to broadcast ECMWF maps?
We tried that. There is no such license to buy.
Everyone, who wants to broadcast ECMWF products or graphics and other Value-Added-Services (VAS) made on basis of ECMWF data has to purchase a broadcast licence separately with ECMWF.
Again, this holds true not only for weathermodels.com, but for any other outlet as well that provides ECMWF maps, charts and other ECMWF based Value-Added-Services.
Can I just cancel my subscription and go to another outlet, because they allow to share ECMWF maps?
No other outlet is allowed to grant any rights to its customers beyond those defined in the ECMWF Standard Licence Agreement, meaning they have to follow the same rules as we do, which are the ones you can find on this guideline page and within our TOS.
Can I use ECMWF model maps from weathermodels.com for my internal commercial purposes?
Yes, you can, if you have bought a commercial license (commercial account type) from us.
Can I use other model maps (ICON, GFS, etc.) from weathermodels.com for my commercial purposes?
Yes, you can if you have bought a commercial license (commercial account type) from us.
ECMWF has general guidelines for their licensees (weathermodels.com) written down here: https://www.ecmwf.int/en/forecasts/access-forecasts/licences-available/guidelines-interpretation-rules-and-standard
November, 2nd 2018