And by future weather, they mean the end of the current month
The science does not exist to make detailed forecasts for temperature and snowfall for the end of this month, let alone for December or even the winter as a whole with these types of forecasts only able to provide an indication of how our weather might change, or be different from normal, (i.e. warmer, colder, wetter, drier) across the whole UK or even Europe.
But, the people who work there have no problem droning on about being able to predict hotcoldwetdry (hey, did the Met Office steal my meme?) 50-100 years down the road.