A Dark Winter can refer to two different things:

1. Dark Winter is a color season that sits between Dark Autumn and True Winter on the seasonal flow chart. It is characterized by dark and cool colors, and high contrast between hair, eyes, and skin. People who are Dark Winter have dark hair and eyes, and cool colors suit them better than warmer ones.

2. Dark Winter is also the name of a tabletop exercise held in 2001 that simulated a bioterrorist attack on the United States using smallpox. The exercise was designed to test the ability of senior officials to respond to a national security crisis. The exercise was a collaborative effort of four organizations, and the scenario was set in three states and involved several federal agencies and foreign governments.

In October 2020, former Vice President Joe Biden used the phrase "dark winter" to describe the potential impact of COVID-19 on the United States. He suggested that the country could face a "twindemic" of flu and COVID-19, and experts warned of a potential rationing of care. Rising trends in daily new cases and deaths at the time supported this assertion.