As with many other geographic features, New Jersey's climate divides into regions. The south, central, and northeast parts of the state have a humid mesothermal climate, while the northwest has a humid continental climate (microthermal), with slightly cooler temperatures due to higher elevation. New Jersey receives between 2,400 and 2,800 hours of sunshine annually.

Summers are typically hot and humid, with statewide average high temperatures of 82–88 °F (28–31 °C) and lows of 60–70 °F (16–21 °C); however, temperatures exceed 90 °F (32 °C) on average 25 days each summer, though rarely exceed 100 °F (38 °C). Winters are usually cold, with average high temperatures of 38–46 °F (3–8 °C) and lows of 26–32 °F (-3–0 °C) for most of the state, but temperatures could, for brief interludes, be as low as 10–20 °F (-12–-7 °C) and sometimes rise to 50–60 °F (10–16 °C). Northwestern parts of the state have slightly colder winters with average temperatures just below freezing. Spring and autumn may feature wide temperature variations, with lower humidity than summer.

Average annual precipitation ranges from 43 to 51 inches (1,100 to 1,300 mm), uniformly spread through the year. Average snowfall per winter season ranges from 10–15 inches (25–38 cm) in the south and near the seacoast, 15–30 inches (38–76 cm) in the northeast and central part of the state, to about 40–50 inches (1.0–1.3 m) in the northwestern highlands, but this varies from year to year. Precipitation falls on an average of 120 days a year, with 25 to 30 thunderstorms, most of which occur during the summer.

During winter and early spring, New Jersey can experience "nor'easters", which are capable of causing blizzards or flooding throughout the northeastern United States. Hurricanes and tropical storms (such as Tropical Storm Floyd in 1999[16]), tornadoes, and earthquakes are rare.