"Winter darkness" refers to the period of time during winter when there is less daylight and the nights are longer. It highlights the lack of sunlight and the darker atmosphere that is common in winter months. Full definition
The dinosaurs had to contend with months of winter darkness and cooler temperatures than environments typically associated with dinosaurs. (sciencedaily.com)
Bad things happen in the long winter darkness, filled with predators, drugs and violence. (metacritic.com)
The people who are fighting to stay in the longer nights, the cozy winter darkness, are doing so because they fear what the light will bring. (madgeniusclub.com)