We have enough coal to see the winter out.
Do I have to say it necessarily before winter starts, or can I say it like three weeks before the end of it?
You can say it at any time.
Context is always important; labelling is rarely important.
You may well be right. It would certainly be unambiguous if you said that in the summer. But if it wasn't winter yet I think I'd say something like 'We have enough coal to see us through till the end of winter.'
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