New Hampshire’s climate is characterized by significant variability, influenced by its northern latitude, mountainous terrain, and proximity to the Atlantic Ocean. The timing of snowfall is highly inconsistent across the state, even over short distances. Elevation and maritime influence dictate when the snow season begins and ends. Understanding the general snow window requires considering the distinct climatic zones within its borders.
Seasonal Onset and Departure
The typical snow season runs from late fall to mid-spring, though specific dates vary regionally. The first measurable snowfall (0.1 inches or more) generally occurs for most of the state between mid-November and mid-December. Higher-elevation areas often reach this benchmark earlier, typically in late October or early November. Lower-elevation southern and coastal regions frequently wait until late November or early December for this initial accumulation.
The departure of the snow season follows a similar gradient, extending the winter period in the northern parts of the state. The last measurable snowfall across the central and southern regions typically occurs between late March and mid-April. Snow can occasionally fall in May, but it is rarely significant or long-lasting outside of the highest mountain peaks. The baseline window for winter precipitation is November to April.
Geographical Differences in Snowfall Timing
The most pronounced differences in snow timing are observed between the state’s northern mountain ranges and its southern coastal plains. Northern regions, particularly the White Mountains and areas above 2,000 feet, experience the earliest onset and the latest departure. Locations like the Presidential Range often see first snowfall in late October, and the snowpack can persist well into May, sometimes into June at the highest elevations. This longer duration is due to colder temperatures and orographic lift, where rising air enhances precipitation.
The Southern Interior and Lakes Region, including cities like Laconia and Keene, represent a transitional zone. In these areas, the first measurable snow usually falls in mid-November, aligning with the state’s average, and the final significant snowfall typically occurs in late March. The timing is less extreme than the mountain regions but is consistently earlier and longer than the coastal zone.
The Seacoast and extreme Southern Tier experience the latest onset and earliest departure. This is due to the moderating influence of the warmer Atlantic Ocean. The ocean’s thermal mass slows fall cooling, delaying the first measurable snow until late November or early December. Warmer maritime air helps melt and prevent late-season snow, leading to the earliest seasonal departure, usually by the end of March.
Peak Snow Season and Accumulation
The heart of New Hampshire’s snow season, when snow is most frequent and accumulation is heaviest, occurs during January and February. During this peak period, the entire state is consistently cold enough to support all-snow precipitation, and major winter storms are most likely to track across the region. These two months consistently deliver the highest monthly totals across all regions, though total annual snowfall varies widely by location.
For a central location like Hanover, average accumulation in January can reach over 18 inches, with February totals remaining high at approximately 16.6 inches. In northern regions, the peak is slightly broader, with Berlin seeing snowfall spread between December and January. In the southern part of the state, however, January often stands out as the distinct peak month for accumulation. This mid-winter period provides the most reliable snow cover, supporting winter recreation and requiring frequent snow removal efforts.