Well pope, if there was a little snowstorm on you as you were chopping the bolts on Town Crier or whatever at Index, in July, you still wouldn't be able to call it a winter ascent.
The rules of the game round here are "it has to be calendar winter to be a winter ascent". You might find "winter conditions" at many times of year but the chest beating must be saved for the times dictated by the Earth's axial tilt.
On the other hand in scotland you can apparently break out the tools for classic summer rock routes any time the temperature is below freezing and there is hoar frost or verglas around, even if it's in October or May, but woe betide anyone who dares touch a crampon point or pick to a climb that is "not in condition" even when it is the middle of February.
Their standard is subjective. Ours is objective. Ours leads to fewer debates. If you want to claim a winter ascent then climb it in calendar winter. If you just want to climb it and don't care if it is a "real" winter ascent or not then just go for it and keep your trap shut when referring to the possibly wintery nature of the ascent.