Early fall =? cold winter.

October 14.

Consider how many leaves there are to fall each year and how much they must add to the soil. We have had a remarkably fertile year.

This year, on account of the very severe frosts, the trees change and fall early, or fall before fairly changing.  

The willows have the bleached look of November.

Let us see now if we have a cold winter.

H. D. Thoreau, Journal, October 14, 1860

The willows have the bleached look of November. See October 15, 1856 (“Banks begin to wear almost a Novemberish aspect. The black willow almost completely bare”); October 17, 1858 ("The Salix lucida lower leaves are all fallen (the rest are yellow). So, too, it is the lower leaves of the willows generally which have fallen first"); October 18, 1853 ("I find my boat all covered — the bottom and seats — with the yellow leaves of the golden willow under which it is moored, and if I empty it, it is full again to-morrow."); October 22, 1857 (“The black willows along the river are about as bare as in November.”); October 24, 1853 ("Black willows bare.")