The Appalachian Mountains play a big part in both the climate and daily weather of West Virginia. Elevation is the key factor in the average temperature and rain and snow variations within the state. On a daily cycle, the mountains can disrupt and weaken, or trigger and strengthen, various weather elements. Some of the heaviest rains and deepest snows have occurred in the Potomac Highland counties of Pendleton, Hampshire, and Hardy, despite this normally being one of the driest areas of the state.

West Virginia's location on the North American continent makes it susceptible to changeable weather, especially from late autumn into early spring. During this time of the year, air masses from the warm and moist Gulf of Mexico region frequently battle with the cold air from the interior of Canada, often clashing over or near West Virginia. Typically, these contrasting conditions oscillate back and forth during the winter season. It can be 65 degrees on a winter day, then snow several inches the next day. The average state temperature for the whole winter season, calculated from all the daily high and low readings, has varied from the mid-20s to the lower 40s.

Occasionally, the upper air currents settle into a stable direction for several weeks. The persistent wind from the northwest during the winter of 1976—77 led to several snowfalls and West Virginia's coldest month on record, January 1977. Terra Alta in Preston County measured 104 inches of snowfall that month, a state record. Other winters that saw prolonged cold include 1894—95, 1903—04, 1904—05, 1917—18, 1935—36, 1962—63, and 1977—78. In those years, snow cover lingered for weeks, rivers froze over, heating costs skyrocketed, transportation was curtailed, and schools closed for many days.

The coldest official temperature on record in West Virginia occurred during one of those winters. The thermometer dropped to 37 degrees below zero at Lewisburg on December 30, 1917. More recently, shorter periods of severe cold occurred in December 1989 and January 1994. In contrast were the extremely mild winters of 1889—90 and 1931—32, when a southwest wind prevailed. Trees were leafing out along the river valleys by February during those years. Communities in the lower elevations often go through mild winters without using their snow shovels; however, a snowstorm on January 20, 1978 delivered 16 inches of snow in Charleston on top of an existing snow cover. The resulting 24 inches of snow, the most on record for the city, paralyzed the Kanawha Valley and closed state government for the day. The most snow to fall from a single storm was 57 inches at Pickens during the great post-Thanksgiving storm of 1950. The most snow in a 24-hour period was 35 inches. This happened at Flat Top, on the Mercer-Raleigh county line, on January 27—28, 1998.

On October 29-30, 2012, Hurricane Sandy pummeled West Virginia, leaving seven people dead and more than 500,000 homes without electricity. Sandy formed in the Caribbean on October 22, and then traveled northward toward the United States. The storm was called a "superstorm" because it merged with a cold front pushed by the polar jet stream. The East Coast experienced high winds, heavy rains, and severe flooding, while the storm produced a blizzard across much of West Virginia. The heavy snow and strong winds toppled trees and roofs and closed roads in several counties, including Nicholas, Tucker, Webster, Preston, Barbour, Randolph, and Kanawha.

During the cold months, when the vegetation is dormant, widespread flooding may occur. This type of flood usually occurs when prolonged rains fall over saturated ground. Snow melt often adds to the runoff. The frequency and severity of river flooding peaked during the late 1800s and the first half of the 20th century. Widespread logging was a direct contributor to that increase in river flooding. Flood control efforts, including dams and flood walls, decreased flooding on many rivers during the last half of the 20th century. Yet, major floods still occurred, including those of November 1985 and January 1996. The Upper Ohio Valley, including Wheeling, was flooded in September 2004.

In sharp contrast to river flooding is the localized cloudburst that may flood only an isolated small creek or hollow. These are the true flash floods. They usually happen during the warm season, May through September. A stationary thunderstorm, or a train of storms passing over the same stream basin, can dump four to eight inches of rain in less than two hours. The affected creeks may rise several feet in minutes. Steep slopes can actually liquefy during these downpours, causing mud, rocks, and even trees to slide down a hillside. The increased urbanization of the state causes faster runoff into once rural streams.

The radar system operated by the National Weather Service can estimate rainfall anywhere in the state. These radars can sense small intense rotation within a thunderstorm, the key ingredient for tornado formation. Large hail can also be inferred from radar data. A network of automatic and manual rain and river gauges are positioned about the state. Nowadays, it's rare for even a flash flood to occur without some advance alert.

Droughts quietly develop over several months and typically last between one and two years. Surface water supply and wells can dry up. Major droughts came during 1894—95, 1930—31, 1953—54, 1963—64, 1965—66, 1987—88, and 1998—99. In 1930, only 9.5 inches of precipitation fell for the entire year at Upper Tract in Pendleton County. Some of the hottest temperatures have occurred during droughts. The hottest state temperature was 112 degrees. It occurred twice, once at Moorefield on August 4, 1930, then at Martinsburg on July 10, 1936.

In 2018 a weather pattern that favored low pressure moving from the Plains into the Tennessee Valley resulted in abundant moisture from the Gulf of Mexico and the western Atlantic into the state. This brought heavy rains in winter and spring, and several locations broke their records for most annual precipitation. Hendricks, three miles southeast of Parsons in Tucker County recorded 96.99 inches of precipitation for the year, breaking the state record of 89.01 inches recorded in 1926 at Bayard in Grant County.