As a lover of autumn, I am guilty of attributing powers to the season that it probably does not possess. For instance, it seems to me that colors are more vivid this time of year. I ascribe this (with absolutely no scientific evidence to support my view) to the slanting yellow sunlight and the cool, atmosphere-cleansing winds of this time of year.
Thus, on a clear, breezy day, the waters of Puget Sound seem the bluest of all blues: azure, cerulean, cobalt, lapis lazuli, and ultramarine rolled into one. With a few white-caps, sails, and seagulls for contrast.
The lake lay blue below the hill.
O'er it, as I looked, there flew
Across the waters, cold and still,
A bird whose wings were palest blue.
The sky above was blue at last,
The sky beneath me blue in blue.
A moment, ere the bird had passed,
It caught his image as he flew.
Theresa Whistler (editor), The Collected Poems of Mary Coleridge (Rupert Hart-Davis 1954). My high school and college French at last comes in handy: "l'oiseau" is "the bird"; "bleu" is "blue."
For another fine evocation of blue, I recommend Andrew Young's "The Nest," which has appeared here previously.