This whole article smells like marketing and a way to monetize their weather model. I hope its leaps and bounds beyond current capability but I have very strong doubts about its efficacy in the real world.
> We’ll be releasing our model’s code, weights, and forecasts, to support the wider weather forecasting community.
https://deepmind.google/discover/blog/gencast-predicts-weath...
They will give you the weights and code not the forecast - your quote is incomplete.
Its either a temporary gift to the community until its adopted then charge for it OR they know most orgs can integrate that into their products therefore requiring to buy google products IF it works as they say it does.