cool breeze of autumn
颸 centers on a specific kind of refreshing wind: the cool breeze of autumn. It is a narrow, poetic term for that seasonal sensation.
颸 combines 風 (wind) with 思, which likely contributes the sound. The character was created to name a specific type of wind.
The wind enclosure 風 wraps around 思 (thought). Imagine a cool autumn breeze that makes you pause and think, carrying the crisp scent of fall.
For シ, picture the cool autumn breeze whispering 'sheee' through the trees: the soft 'she' sound cues シ while the wind rustles the leaves.