Maryland’s position in the Mid-Atlantic region results in a transitional climate, heavily influenced by the Atlantic Ocean and the mountainous terrain to the west. This geography causes winter conditions to be highly variable, leading to significant annual fluctuations in temperature and snowfall. The state experiences a full winter season, but the consistency and total accumulation of snow differ greatly depending on the specific location. Understanding snowfall requires looking at both the calendar timing and the distinct geographic zones that determine accumulation.
Defining the Snow Season
The potential period for snowfall in Maryland typically begins in mid-November and extends into early April. While flurries might occur earlier in Western Maryland’s highest elevations, measurable snow usually starts around Thanksgiving. The state’s primary winter season runs from December through March.
The peak months for snow accumulation across the state are historically January and February. These months consistently feature the lowest average temperatures and the most frequent strong winter storm systems. Early and late season events, such as snow in November or a significant spring snowstorm in March, are less common.
March often brings a notable contrast between the eastern and western parts of the state. While coastal areas see a rapid decline in snow chances, Western Maryland’s mountainous regions can still experience substantial snowfall. Shoulder month snowfall tends to be lighter and melts quickly, while mid-season events result in prolonged coverage.
Regional Differences in Snow Accumulation
Maryland’s topography creates significant differences in average annual snow totals, which are dependent on location. The state can be divided into three distinct zones of accumulation, ranging from over 100 inches in the west to less than 10 inches on the coast. This variability results directly from elevation and the moderating effects of nearby bodies of water.
Western Maryland/Appalachian Region
This region, which includes Garrett and Allegany counties, receives the state’s highest snowfall totals due to its higher elevation and proximity to the Great Lakes. The town of Oakland, for example, averages over 100 inches of snow annually. The city of Frostburg also sees heavy accumulation, averaging over 70 inches per year.
The high altitude ensures temperatures remain colder, meaning precipitation falls as snow rather than rain. This area is susceptible to lake-effect enhancement, where cold air moving over Lake Erie creates intense snow bands. Even within this region, totals vary; valley locations like Cumberland average 28 inches.
Central Maryland/Piedmont
The central portion of the state, including the Baltimore and Washington D.C. metropolitan areas, experiences moderate and inconsistent snowfall. Locations in this zone, such as Baltimore-Washington International Airport (BWI), typically average around 19 to 20 inches of snow per winter season. The terrain here is characterized by rolling hills that create microclimates.
Accumulation totals increase quickly over short distances when traveling northwest and gaining elevation away from the Chesapeake Bay. Areas in the northwest suburbs of Baltimore and northern Frederick County, which rise to elevations around 1,000 feet, can average over 30 inches annually. This zone frequently sits near the rain/snow line during major winter storms, resulting in unpredictable outcomes.
Eastern Shore/Coastal Areas
The Eastern Shore and coastal parts of Southern Maryland receive the lowest average annual snowfall due to the moderating influence of the Atlantic Ocean and the Chesapeake Bay. This influence keeps air temperatures near or above freezing during many precipitation events, often leading to rain or a mix of rain and snow. Coastal towns like Salisbury often average less than 10 inches per year.
In the most coastal areas, such as Assateague Island, the average annual total can be as low as 3 to 4 inches. The proximity to the ocean and the low elevation mean that even during a large storm, this region is often the first to change over from snow to rain. This battle with the rain/snow line is the primary factor limiting accumulation in the eastern half of the state.
Weather Systems Driving Maryland Snow
Maryland’s winter weather is driven by three primary types of atmospheric systems. The most impactful events are caused by coastal low-pressure systems, commonly known as Nor’easters. These storms develop off the Atlantic coast, drawing significant moisture from the ocean.
A Nor’easter’s track determines whether the state receives heavy snow or a mix of snow, sleet, and freezing rain. These storms are responsible for the heaviest snowfalls, often bringing multi-foot totals. The rain/snow line often settles over the I-95 corridor, creating a sharp division between heavy snow to the northwest and rain to the southeast.
The second common system is the fast-moving low-pressure area, referred to as a clipper system, which descends from Canada. These systems move quickly and lack the deep moisture of a Nor’easter, usually resulting in lighter snowfalls of one to three inches. Clippers bring brief bursts of snow and usher in colder arctic air.
Localized enhancement effects from nearby bodies of water also affect the state. The far western counties experience lake-effect enhancement from the Great Lakes, boosting their snowfall totals. When frigid air passes over the Chesapeake Bay, it can generate narrow bands of “bay-effect” snow that briefly impact areas downwind on the Eastern Shore.