I don't ever remember looking at an autumn sky and saying "wow, there's the first winter cloud" but every year about this time I look skyward and see my first summer cloud. It is an event that is fully as heart- clutching as seeing the first geese, but the geese are more predictable. You know to listen for them on the first south wind after the weather makes a pronounced break.
The first summer cloud of 2003; just a little nub of cumulus, dancing upon the flat winter clouds.