2023–24 North American winter

The 2023–24 North American winter was the warmest winter on record across the contiguous United States, with below-average snowfall primarily in the Upper Midwest and parts of the Northeastern United States. However, some areas, especially in the states of Pennsylvania, New Jersey and New York saw considerably more snow than the previous winter. Notable winter events were also more prevalent across the eastern half of the country this winter, including a series of winter storms in mid-January that brought snow from the South to Northeast states, a period of very cold temperatures across much of the continent in mid-to-late January, and a disruptive nor'easter that affected much of the Mid-Atlantic in mid-February. Additional events included in other places included a record-breaking blizzard that struck Canada and atmospheric river events in California, both in the month of February. Two storms were rated on the Regional Snowfall Index (RSI), although none attained a "Major" rating (Category 3+) on the scale. A strong El Niño was expected to influence the winter weather patterns across the continent. The winter weather-related events this season led to an estimated US$10 billion in damages, and an estimated 106 fatalities, much of it occurring in the month of January.

While there is no well-agreed-upon date used to indicate the start of winter in the Northern Hemisphere, there are two definitions of winter which may be used. Based on the astronomical definition, winter begins at the winter solstice, which in 2023 occurred on December 21, and ends at the March equinox, which in 2024 occurred on March 19. Based on the meteorological definition, the first day of winter is December 1 and the last day February 29. Both definitions involve a period of approximately three months, with some variability. Winter is often defined by meteorologists to be the three calendar months with the lowest average temperatures. Since both definitions span the calendar year, it is possible to have a winter storm spanning two different years.