Winter storm facts for kids

A winter storm is a weather event where strong winds combine with different types of precipitation that only happen when temperatures are at or below freezing point (0°C or 32°F). This precipitation can be snow, a mix of snow and rain, or freezing rain. These storms often happen in winter, but they can also occur in late autumn and early spring in places with cold climates. When a snowstorm has very strong winds and makes it hard to see, it's called a blizzard.

Heavy snowfall and strong winds during a 2016 blizzard in New York City.

National Guard members clearing a road after a February 2021 winter storm in Putnam County, West Virginia.

How Winter Storms Form

Winter storms begin when moist air rises high into the atmosphere. This creates an area of low pressure near the ground and forms clouds in the sky. Sometimes, hills or mountains can also push air upwards. This upward movement of air is called lift. The air collects moisture from large bodies of water, like big lakes or the ocean.

If the temperature is below freezing (0°C or 32°F) both near the ground and high in the clouds, the precipitation will fall as snow, ice, rain and snow mixed (sleet), ice pellets, or even graupel (soft hail). Cold air cannot hold as much moisture as warm air, so the total amount of precipitation in a winter storm might be less than in a warm-weather storm.

Winter Storm Warnings: What to Look For

Weather experts issue winter storm warnings to help people stay safe. A warning might be issued if:

• Snowfall reaches 6 inches (15 cm) or more in 12 hours, or 8 inches (20 cm) or more in 24 hours.
• Blowing snow makes it very hard to see over large areas, even with winds less than 35 mph (56 km/h).
• Ice builds up on surfaces by 0.25 inches (0.64 cm) or more.
• Ice pellets larger than 1 inch (2.5 cm) are expected.
• The Wind chill index drops below -35°F (-37°C) for more than 3 hours, with steady winds of at least 10 mph (16 km/h).

Snowstorms with winds faster than 35 mph (56 km/h) and visibility less than 0.25 miles (400 m) for 3 hours or longer are called blizzards.

Understanding Winter Storm Terms

The term "winter storm" can describe different things. It might be a local weather event that lasts for a day. Or, it could be a huge storm system that covers a large part of a continent for several days. For very large winter storms, people often call the weather a "storm" even if every single spot doesn't meet all the strict weather criteria. For example, the February 13–17, 2021 North American winter storm brought snow and freezing temperatures as far south as Texas and the Gulf of Mexico.

What is a Snowstorm?

Snowstorm in Oulu, Finland

Chicago's Fullerton Harbor looking south during the January 31 – February 2, 2011, North American winter storm (left) and on a clear day for comparison.

Snowstorms are storms where a lot of snow falls. Even just 2 inches (5 cm) of snow can cause big problems for traffic and school buses, especially in places where heavy snow isn't common. It becomes difficult to drive on slippery roads. In areas where snow is normal, small snowfalls usually don't cause many issues. This is because cities are good at clearing snow and ice, and drivers are more used to winter conditions. However, snowfalls over 6 inches (15 cm) usually cause disruptions everywhere.

Some very serious snowstorms have happened in history. For example, the North American blizzard of 1947 brought over 2 feet (60 cm) of snow, with huge snow piles reaching 12 feet (3.7 m) high that lasted for months. The 1993 "Superstorm" was another massive blizzard that affected many areas.

Snowfall Dangers

Heavy snow can make driving very dangerous. Snow on roads reduces how much grip tires have, making it much harder to steer a vehicle. This can slow down driving speeds by a lot. Falling snow also makes it hard to see, and strong winds often make this even worse. In extreme cases, you might experience a whiteout, where you can only see a few feet in front of you because of the snow. These dangers can continue even after the snow stops falling if strong winds pick up the fallen snow and blow it around.

If a vehicle gets stuck in deep snow, it can be very dangerous. Snow can block a car's exhaust pipe, leading to carbon monoxide building up inside the car. Carbon monoxide is a colorless, odorless gas that can be very harmful.

Snow can be either wet or dry. Dry snow is lighter and blows around more easily, forming tall drifts. Wet snow is heavier because it contains more water. A lot of heavy wet snow can damage roofs. Shoveling heavy wet snow can also be very strenuous, so it's important to be careful and take breaks. When wet snow sticks to elevated surfaces, it can cause a lot of damage to trees and power lines, similar to what happens in ice storms.

If power is lost during a major winter storm, buildings can lose their heating. Besides the risk of getting too cold (hypothermia), another danger is carbon monoxide poisoning. This can happen if fumes from generators or heating devices are not properly vented outside. Also, snow that melts on roads can refreeze when temperatures drop, creating black ice, which is very slippery and hard to see.

Snow storm in Modena, Italy

Wet snow and sleet during a winter storm, on the deck of RFA Tidespring south of Plymouth in the English Channel.

Freezing Rain and Ice Storms

Coated in ice, power and telephone lines sag and often break, resulting in power outages.

Hawthorn berries covered in icy glaze due to freezing rain. Ice storms often coat many surfaces. Severe ice storms can damage plants.

Heavy showers of freezing rain are one of the most dangerous types of winter storm. They happen when a layer of warm air is above a region, but the air a few meters above the ground, and the ground itself, are at or below freezing (0°C or 32°F). The rain falls through the warm air, then freezes instantly when it hits cold surfaces on the ground.

While 10 cm (4 inches) of snow can be managed in places used to winter weather, even a small amount of ice, like 10 mm (0.4 inches), can paralyze a region. Driving becomes extremely dangerous, telephone and power lines can break, and plants may be damaged.

Famous Ice Storms

Many notable ice storms have occurred throughout history. A very serious ice storm in 1998 affected much of eastern Canada, including cities like Montreal and Ottawa, as well as parts of New York and New England. Three million people lost power, some for as long as six weeks. Many trees were damaged, including a large number of sugar-producing maple trees.

Other significant ice storms include:

• The 2000 Christmas Day Ice Storm, which caused major electrical problems in parts of Arkansas, Oklahoma, and Texas.
• The North Carolina ice storm of 2002, which led to massive power loss and property damage from falling trees.
• The December 2005 North American ice storm, which caused widespread ice damage across the Southern United States and led to power outages.
• The January 2009 North American ice storm, a very severe storm where many places saw 2 inches (5 cm) or more of ice. This brought down power lines, leaving over 2 million people without electricity for days or even weeks.
• The February 13-17, 2021 North American winter storm was a very serious winter storm that affected most of the central and southern United States. The state of Texas experienced widespread power outages for 7–10 days due to the storm's impact on its power system.

How to Prepare for Winter Storms

2008 Chinese winter storm in Hefei, Anhui Province, China

In countries where winter storms are common, governments and health organizations offer advice on how to get ready for severe weather. While specific tips might vary, some important advice includes:

• Stock up on enough food, water, medicines, and hygiene items for at least three days.
• Keep warm clothes ready.
• Have a flashlight and extra batteries.
• Stay informed by checking weather updates.
• Help your family and neighbors.
• Avoid traveling unless it is absolutely necessary.

Learn More About Winter Weather