Fur primes as we lose daylight. Less daylight/shorter days = fur starts to prime
nothing to do with when an early cold snap arrives, it's the amount of daylight that spurs hair growth.
Most of the Coyotes I killed this summer had clean, shiny fur. Real nice, lightweight summer coat.
Winter prime fur has dense under fur with long guard hairs.
I watch our Cat's fur thicken. He even gets more fur between his toes.