Climate Matters•December 21, 2022
The Warming Festive Season
KEY CONCEPTS
If you’re dreaming of a white Christmas, Hanukkah, or Kwanzaa this year… historical odds are highest in Idaho, Minnesota, Maine, Upstate New York, and in the Allegheny, Rocky, or Sierra Nevada Mountains.
Snow feeds water supplies and supports economies. But these benefits melt away when the timing and amount of snowfall shifts.
As the planet warms, observed changes in snowpack, snowfall, and the length of snow seasons vary among U.S. regions.
The Twelve Days of Christmas are also warming. 97% of the 246 locations analyzed have experienced an increase in average temperature for this 12-day period since 1969.
If you’re dreaming of a white Christmas, Hanukkah, or Kwanzaa this year…
Based on NOAA’s analysis of the most recent climate normals (1991-2020), the historical probabilities of at least 1 inch of snow accumulation on December 25 are best in Idaho, Minnesota, Maine, Upstate New York, and the Allegheny, Rocky, or Sierra Nevada Mountains.
The historical probability of a white Christmas is slimmer for the rest of the contiguous U.S.
Snow feeds water supplies and supports economies. But these benefits melt away when the timing and amount of snowfall shifts.
Winter is the fastest-warming season for most of the U.S., and warmer winter air can hold more moisture.
But where that moisture falls—and whether it falls as rain or snow—mainly depends on local temperatures. Fewer freezes raise the odds of moisture falling as rain—not snow.
Changes in the timing, location, and amount of snowfall vary among regions:
In the western U.S., mountains act as natural water towers, storing snow that makes up more than half of the region’s water supply. But since the 1950s, the western U.S. has experienced declining snowpack, earlier snowmelt, and a shift toward less precipitation falling as snow.
In the Northeast, the proportion of winter precipitation falling as rain rather than snow has increased—a trend that is projected to continue over this century. With continued warming, the region’s winter recreation season is likely to become shorter and smaller.
In the Great Lakes region, annual maximum lake ice cover has declined by 22% on average across all of the Great Lakes since 1973. Longer periods of open water can lead to more evaporation and to an increase in lake effect snow.
In the Northern Great Plains, warming has led to shorter snow seasons and a decline in snowpack water storage—leading to lower snowmelt-fed streamflows that affect aquatic ecosystems and the local economics and recreation industries that depend on them.
The Twelve Days of Christmas are also warming. Climate Central analysis of temperature data at 246 U.S. locations shows widespread warming during the Twelve Days of Christmas since 1969.
97% of the 246 locations analyzed have experienced an increase in average temperature for this 12-day period (December 25 to January 5) from 1969 to 2021.
Warming exceeded 1°F for 94% of locations, 3°F for 75% of locations, and 5°F for 37% of locations.
Temperatures have climbed from coast to coast. The locations that have warmed the most are: Reno, Nev. (9.5°F); Burlington, Vt. (9.1°F), Milwaukee, Wisc. (8.6°F), Helena, Mont. (8.5°F), and Waterloo, Iowa (8.4°F).
POTENTIAL LOCAL STORY ANGLES
Will you be having a snowy festive season?
NOAA’s interactive map provides a guide to the historical probability of at least 1 inch of snow accumulation on December 25 near you based on the last 30 years of weather data. Launch an interactive map, get a KMZ version, and download the raw data on NOAA’s website. Check your local forecast within a week of the holidays you celebrate for the actual weather conditions up on your rooftop this year.
What’s the snow forecast for where you live?
The National Weather Service’s Winter Page provides maps and forecasts for snow and ice in your area. Their Winter Weather Desk provides twice-daily local forecasts for snow and freezing rain. Criteria for winter storm watches, advisories, and warnings can vary by region so check out your local National Weather Service office. The NWS also provides helpful information on how to stay safe in winter conditions.
LOCAL EXPERTS
The SciLine service, 500 Women Scientists or the press offices of local universities may be able to connect you with local scientists who have expertise on winter warming, snowfall, and climate change. The American Association of State Climatologists is a professional scientific organization composed of all state climatologists.
NATIONAL EXPERTS
John Bateman
Public Affairs Officer
NOAA/NESDIS/NCEI
Contact: nesdis.pa@noaa.gov
METHODOLOGY
White Christmas probabilities represent the historic chance of at least 1 inch of snow depth on 12/25 based on 1991-2020 climate normals. NOAA/NCEI calculated probabilities for thousands of U.S. stations. Of the 247 stations typically used in Climate Matters analyses, 183 had sufficient data to determine historical white Christmas probabilities. For the remaining 64 locations, the probability of the nearest station with sufficient data was used. Graphic footnotes indicate the station ID used for each market. Detailed methodology, including limitations and caveats, can be found on Climate.gov.
Average temperatures were calculated for the period from December 25 - January 5 for 1969-70 to 2020-21 using data obtained from the Applied Climate Information System. Climate Central's local analyses include 247 stations. However, for data summaries based on linear trends, only 246 stations are included due to large data gaps in Wheeling, W.Va.