Delaware experiences four distinct seasons, which include cold winter months. While snowfall is a regular part of the winter climate, the yearly accumulation can be highly variable across the entire state. The winter season generally brings temperatures cold enough to support snow, though the amount received depends heavily on specific weather patterns and geographic location.
Geographic Variations in Delaware’s Snowfall
Delaware’s small size belies a significant difference in snowfall amounts between its northern and southern regions. Northern Delaware, specifically New Castle County, typically receives the highest annual snowfall totals. This area is geographically situated further from the moderating effects of the Atlantic Ocean, resulting in colder air masses and higher snow accumulation.
In contrast, Southern Delaware, encompassing Sussex County and the Atlantic coastline, sees considerably less snow each year. The proximity of the ocean and the Delaware Bay introduces a maritime influence that often keeps temperatures just above freezing. This warmer environment means that winter precipitation is more likely to fall as rain or a mix of rain and snow rather than purely as snow.
Coastal towns, such as Lewes, often experience the lowest totals in the state. A single storm system can easily drop over 15 inches in the northern part of the state while the beaches only receive a few inches. This regional disparity means residents’ winter experiences can differ dramatically across the state.
Statistical Look at Annual Snow Amounts and Frequency
The average annual snowfall for Delaware ranges broadly from approximately 9 to 20 inches, demonstrating the state’s climatic variability. Wilmington, the state’s largest city in the north, averages about 20.2 inches of snow annually based on 1991-2020 data, reflecting the higher totals in New Castle County. Coastal towns like Lewes, however, average closer to 10.5 inches per year, highlighting the significant decrease toward the south and the coast.
The typical timeframe for the snow season runs from December through March, with the heaviest snow accumulations usually occurring in January and February. Wilmington averages about 3.5 days in both January and February where measurable snow falls (defined as 0.1 inches or more).
The entire state generally experiences measurable snowfall on a few days each year, with locations like Dover averaging 4.9 days and Wilmington averaging 10.7 days of snow annually. While the averages provide a baseline, Delaware’s snowfall is known for its high year-to-year variability.
Some winters see very little snow while others are marked by significant, multi-day events. The first snowfall usually arrives in December, and the last typically occurs in March.
Weather Patterns That Bring Significant Snow
The largest and most impactful snow events in Delaware are often brought by powerful low-pressure systems known as Nor’easters. These storms develop along the East Coast and track northeastward, drawing moisture from the Atlantic Ocean and cold air from the continental interior. The precise track of a Nor’easter is a major factor in determining how much snow falls across the state.
A storm track that passes just offshore is most likely to bring heavy snow to the northern and central counties. When the storm tracks too far out to sea, the precipitation misses the state entirely. When it tracks too close to the coast, the warmer ocean air often causes the snow to change to rain, especially along the shoreline.
The Atlantic Ocean’s influence provides the moisture necessary for large storms, but the relatively warm sea surface temperatures can limit the duration of snowfall near the coast. During these Nor’easters, the state can experience blizzard-like conditions with strong winds, which can lead to significant drifting and coastal flooding.
The heaviest snowfalls are a result of this interplay between the deep moisture of the ocean and the cold air drawn down from the north. Even a powerful coastal storm can sometimes deliver its highest snow totals to Kent and Sussex counties.