January Is When Winter's Worst Snow, Cold Peaks For Many In US

Winter's worst weather conditions can occur in multiple months, but January is a peak snowfall time for many and has historically seen a ramp up in the chance of major East Coast snowstorms late in the month. It's also the coldest time of year across a large part of the country.

January ranks as either the first- or second-snowiest month in many parts of the U.S. The first month of the new year is on average the snowiest in parts of the Great Lakes, Midwest and Rockies, based on the map below produced by Alaska-based climatologist Brian Brettschneider. The map shows those locations where January is the snowiest month in dark pink, according to 1991-2020 data.

C​hicago (11.3 inches), Cleveland (18.4 inches), Salt Lake City (12.7 inches) and St. Louis (5.7 inches), are some of the larger cities where January is the snowiest month.

J​anuary is the second-snowiest month in many other parts of the U.S., as shaded in lighter pink.

(​MORE: What Month Is Snowiest Where You Live?)

Late-January marks the start a 40-plus-day sweet spot for big Northeast snowstorms: January and February are neck and neck when it comes to the top two snowiest months along the Eastern Seaboard. For example, Boston's average snowfall is 14.3 inches in January and 14.4 inches in February. New York City has averaged 8.8 inches in January and 10.1 Inches in February.

Based on the Northeast Snowfall Impact Scale (NESIS), which ranks East Coast winter storms Category 1 to 5, late in the month is when the frequency of major Northeast snowstorms has historically increased. In general, widespread heavy snowfall over highly populated areas produces a higher NESIS value and therefore a higher category ranking.

A​s the graph below shows, the 36 Northeast snowstorms that were Category 3 or higher on the NESIS scale from 1956 to 2022 have happened from December through early March, according to NOAA's National Centers for Environmental Information.

Dividing those storms into halves of months reveals there's a distinct peak in their frequency beginning in late January and lasting through mid-February.

J​anuary sees temperatures plummet to their coldest day of the year for many. From the Northern Plains to the Midwest, Southeast and Northeast, the last two weeks of January are typically the coldest time of year. That's based on the map below which shows when the average coldest day of the year typically occurs in the United States, according to 1991-2020 data from NOAA.

January is also the coldest time of year in Alaska.

From the Front Range of the Rockies westward, the coldest time of year is in early January or even before then in December.

Chris Dolce has been a senior meteorologist with weather.com for over 10 years after beginning his career with The Weather Channel in the early 2000s.