Climate

                       Climate

New Hampshire experiences a humid continental climate (Koppen climate classification Dfa in southern areas and Dfb in the north), with warm, humid summers, cold, wet winters, and uniform precipitation all year. The climate of the southeastern portion is moderated by the Atlantic Ocean and averages relatively milder and wetter weather, while the northern and interior portions experience cooler temperatures and lower humidity. Winters are cold and snowy throughout the state, and especially severe in the northern and mountainous areas. Average annual snowfall ranges from 60 inches (150 cm) to over 100 inches (250 cm) across the state.

Average daytime highs are in the mid 70s°F to low 80s°F (around 24-28 °C) throughout the state in July, with overnight lows in the mid 50s°F to low 60s°F (13-15 °C). January temperatures range from an average high of 34 °F (1 °C) on the coast to overnight lows below 0 °F (-18 °C) in the far north and at high elevations. Average annual precipitation statewide is roughly 40 inches (100 cm) with some variation occurring in the White Mountains due to differences in elevation and annual snowfall.

Extreme snow is often associated with a nor'easter, such as the Blizzard of '78 and the Blizzard of 1993, when several feet accumulated across portions of the state over 24 to 48 hours. Lighter snowfall of several inches occur frequently throughout winter, often associated with an Alberta Clipper.

New Hampshire, on occasion, is affected by hurricanes and tropical storms although by the time they reach the state they are often extratropical, with most storms striking the southern New England coastline and moving inland or passing by offshore in the Gulf of Maine. Most of New Hampshire averages fewer than 20 days of thunderstorms per year and an average of 2 tornadoes occur annually statewide

The National Arbor Day Foundation plant hardiness zone map depicts zones 3, 4, 5, and 6 occurring throughout the state and indicates the transition from a relatively cooler to warmer climate as one travels southward across New Hampshire.