October 11, 1852 in Thoreau’s Journal:

Now it is true autumn—all things are crisp & ripe.

October 11, 1859:  

The note of the chickadee heard now in cooler weather  & above many fallen leaves––has a new significance.  

There was a very severe frost this Am prob ground stiffened a chestnut-opening frost.  A season-ripener––opener of the burrs that enclose the Indian summer––  Such is the cold of early or mid October.  The leaves and weeds had that stiff hoary appearance.