An ice storm which struck northern Idaho in January 1961 set a record for thickest recorded ice accumulation from a single storm in the United States, at 8 inches.

In 1994, a severe ice storm caused over $1 billion in damage in the Southern United States in February 1994, primarily in Mississippi, Tennessee, and Alabama.

The North American ice storm of 1998 occurred during January 5–9, 1998. It was one of the most damaging and costly ice storms in North American history. The storm caused massive power failures in several large cities on the East Coast of the United States. The most affected area was extreme eastern Ontario and southwestern Quebec in Canada, where over 3 million people were without power for up to a month and a half. Whole trees snapped and electrical pylons were completely flattened under the weight of the accumulated ice.

The Northeastern United States was impacted by a major ice storm on December 11–12, 2008, which left about 1.25 million homes and businesses without power. Areas impacted with 3/4" to 1" of ice accumulation included eastern New York in the Albany area, central and western Massachusetts, southern New Hampshire, coastal and south-central Maine, Pennsylvania in the Pocono Mountains region, northwestern Connecticut, and southern Vermont. Southern New Hampshire and northernmost Massachusetts got hit the worst with the storm with ice accumulations ranging from 1.5 in to 3 in of ice. This left residents unable to get supplies, go to work etc. due to blocked roads from trees that fell on the roads. Any trees that fell quickly took down power poles. It took utility crews from 4 to as much as 16 days to get a look at the damage and start to restore power to nearly 1.3 million people. In all there were 675,000 residents in New Hampshire without power and around 500,000 in northern Massachusetts

In late January, 2009, ice storms covered several U.S. states, including Arkansas and Kentucky. Most areas affected saw over 2" of ice accumulation, and between 1"–5" of snow on top of the ice. This ice storm left well over 2 million people without power at its peak and killed 55 people, 24 in Kentucky. Rural Water Associations in Arkansas and Kentucky activated emergency response plans to deal with power loss to small water utilities across their states. Neighboring state Rural Water Associations, including experienced emergency responders from Louisiana and Florida, loaned equipment and manpower to assist the hardest-hit areas.

During the unusually severe winter of 2009–2010 in the United Kingdom, heavy snow had fallen over much of the country in late December and early January. By the second week of January, many of the roads and pavements had been cleared by local councils due to the use of rock salt gritting. However, during the early hours of 12 January, a wet front moved across the country, causing freezing rain and heavy ice glaze, particularly in the South and West Yorkshire areas of Northern England (crucially, this rainfall had stopped before first light). When the local population prepared to set out for work and school, they saw from their windows what appeared to be clear roads and pavements but were in fact treacherous sheets of black ice. Cars and buses almost immediately encounted extreme difficulty, and emergency services were called to dozens of accidents. Pedestrians in the village of Holmfirth found the only safe way to proceed was to crawl on all fours. Accident and emergency units at hospitals in the Sheffield, Rotherham, and Barnsley areas found themselves inundated by people with broken bones, fractures, and sprains, and many schools were closed as it was judged unsafe for pupils to attempt to make their way there.

On December 25, 2010, freezing rain fell on Moscow and vicinity. The glaze ice accumulation caused a number of accidents and power outages, of which the most serious was damage caused to two power lines feeding Domodedovo Airport, causing a complete blackout of the airport and express railway that connected it to the city. As a result, the airport was shut down and hundreds of passengers were stranded inside, with taxi drivers charging up to 10,000 rubles (USD 330) for a one-hour drive to the city. Other city airports, Sheremetyevo and Vnukovo, where air traffic was re-routed and amid heavy snowfall that followed ice rain, collapsed a day later, causing a full air transport collapse.

The freezing rain from an ice storm covers everything with heavy, smooth glaze ice. Ice-covered roads become slippery and hazardous, as the ice causes vehicles to skid out of control, which can cause devastating car crashes as well as pile-ups. Pedestrians are severely affected as sidewalks become slippery, causing people to slip and fall, and outside stairs can become an extreme injury hazard.

In addition to hazardous driving or walking conditions, branches or even whole trees may break from the weight of ice. Falling branches can block roads, tear down power and telephone lines, and cause other damage. Even without falling trees and tree branches, the weight of the ice itself can easily snap power lines and also break and bring down power/utility poles; even steel frame electricity pylons have been sent crashing to the ground by the weight of the ice. This can leave people without power for anywhere from several days to a month. According to most meteorologists, just one quarter of an inch of ice accumulation can add about 500 pounds of weight per line span. Damage from ice storms is highly capable of shutting down entire metropolitan areas.

Additionally, the loss of power during ice storms has indirectly caused numerous illnesses and deaths due to unintentional carbon monoxide (CO) poisoning. At lower levels, CO poisoning causes symptoms such as nausea, dizziness, fatigue, and headache, but high levels can cause unconsciousness, heart failure, and death. The relatively high incidence of CO poisoning during ice storms occurs due to the use of alternative methods of heating and cooking during prolonged power outages, common during severe ice storms. Gas generators, charcoal and propane barbecues, and kerosene heaters contribute to CO poisoning when they operate in confined locations. CO is produced when appliances burn fuel without enough oxygen present, such as basements and other indoor locations.

Loss of electricity during ice storms can also easily lead to hypothermia and even death from hypothermia. It can also lead to ruptured pipes due to water freezing inside the pipes.

Tree sensitivity to sap coloration and resistance to crown damage from an ice storm.

Sensitivity to sap coloration	Resistance to ice damage to crown
	Low or average	Average or strong	Strong
Sensitive	Manitoba maple (Acer negundo) Pennsylvania maple Silver maple (Acer saccharinum) Norway maple (Acer platanoides) Red Maple (Acer rubrum) White birch (Betula pubescens) Grey birch (Betula populifolia) Jack pine (Pinus banksiana) Red pine (Pinus resinosa) Aspens Pin cherry (Prunus pensylvanica) Chokecherry (Prunus virginiana) Willows and Alders Mountain ashes Linden (or basswood) Locusts and Honey locusts (Gleditsia triacanthos)	Yellow birch (Betula alleghaniensis) American beech (Fagus grandifolia) White ash (Fraxinus americana) Elms Sugar Maple (Acer saccharum) White pines Apple trees Balsam fir (Abies balsamea) Little-leaf linden (Tilia cordata) Hawthorns	Spruces
Insensitive	Eastern white cedar (Thuja occidentalis) American larch (Larix laricina) Black cherry (Prunus serotina) Red ash (Fraxinus pennsylvanica) Common hackberry (Celtis occidentalis)	Bitternut hickory (Carya cordiformis) Red oaks Tree of Heaven (Ailanthus altissima) Black ash (Fraxinus nigra) Shagbark hickory (Carya ovata)	Eastern hemlock (Tsuga canadensis) Burr oak (Quercus macrocarpa) White oak (Quercus alba) Swamp white oak (Quercus bicolor) Hophornbeam Black walnut (Juglans nigra) Hornbeam Saskatoon berry (Amelanchier alnifolia)

Ice storms occur when a layer of warm air is between two layers of cold air. Frozen precipitation melts while falling into the warm air layer, and then proceeds to refreeze in the cold layer above the ground. If the precipitate is partially melted, it will land on the ground as sleet. However, if the warm layer completely melts the precipitate, becoming rain, the liquid droplets will continue to fall, and pass through a thin layer of cold air just above the surface. This thin layer of air then cools the rain to a temperature below freezing (0 °C). However, the drops themselves do not freeze, a phenomenon called supercooling (or forming "supercooled drops"). When the supercooled drops strike ground below 0 °C or anything else below 0 °C (power lines, tree branches, aircraft), they instantly freeze, forming a thin film of ice, hence freezing rain.

While meteorologists can predict when and where an ice storm will occur, some storms still occur with little or no warning. Most ice storms are thought to form primarily in the north-eastern US, but damaging storms have occurred farther south. An ice storm in February 1994 resulted in tremendous ice accumulation as far south as Mississippi, and caused reported damage in nine states. More timber was damaged than that caused by Hurricane Camille. An ice storm in eastern Washington in November 1996 directly followed heavy snowfall. The combined weight of the snow and 25 millimetres (0.98 in) to 37 millimetres (1.5 in) of ice caused considerable widespread damage. This was considered to be the most severe ice storm in the Spokane area since 1940.

An ice storm is a type of winter storm characterized by freezing rain, also known as a glaze event or in some parts of the United States as a silver thaw. The U.S. National Weather Service defines an ice storm as a storm which results in the accumulation of at least 0.25-inch (0.64 cm) of ice on exposed surfaces. From 1982 to 1994, ice storms were more common than blizzards and averaged 16 per year.

Heavy showers of freezing rain are one of the most dangerous types of winter storm. They typically occur when a layer of warm air hovers over a region, but the ambient temperature is near 0 °C (32 °F), and the ground temperature is sub-freezing. A storm in which only roads freeze is called a freezing rain storm; one resulting in widespread icing of plants and infrastructure is called an ice storm.

While a 10 cm (4 in) snowstorm is somewhat manageable by the standards of the northern United States and Canada, a comparable 1 cm (0.4 in) ice storm will paralyze a region: driving becomes extremely hazardous, telephone and power lines are damaged, and crops may be ruined. Because they do not require extreme cold, ice storms often occur in warm temperature climates (such as the southern United States) and cooler ones. Ice storms in Florida will often destroy entire orange crops.

Notable ice storms include an El Niño-related North American ice storm of 1998 that affected much of eastern Canada, including Montreal and Ottawa, as well as upstate New York and part of New England. Three million people lost power, some for as long as six weeks. One-third of the trees in Montreal's Mount Royal park were damaged, as well as a large proportion of the sugar-producing maple trees. The amount of economic damage caused by the storm has been estimated at $3 billion Canadian.

The Ice Storm of December 2002 in North Carolina resulted in massive power loss throughout much of the state, and property damage due to falling trees. Except in the mountainous western part of the state, heavy snow and icy conditions are rare in North Carolina.

The Ice Storm of December 2005 was another severe winter storm producing extensive ice damage across a large portion of the Southern United States on December 14 to 16. It led to power outages and at least 7 deaths.

In January 2005 Kansas had been declared a major disaster zone by President George W. Bush after an ice storm caused nearly $39 million in damages to 32 counties. Federal funds were provided to the counties during January 4–6, 2005 to aid the recovery process.

The January 2009 Central Plains and Midwest ice storm was a crippling and historic ice storm. Most places struck by the storm, saw 2 inches or more of ice accumulation, and a few of inches of snow on top it. This brought down power lines, causing some people to go without power for a few days, to a few weeks. In some cases, some didn't see power for a month or more. At the height of the storm, more than 2 million people were without power.

Snowstorms are storms where large amounts of snow fall. Snow is less dense than liquid water, by a factor of approximately 10 at temperatures slightly below freezing, and even more at much colder temperatures. Therefore, an amount of water that would produce 0.8 in. (2 cm.) of rain could produce at least 8 in (20 cm) of snow. Two inches of snow (5 cm.) is enough to create serious disruptions to traffic and school transport (because of the difficulty to drive and maneuver the school buses on slick roads). This is particularly true in places where snowfall is uncommon but heavy accumulating snowfalls can happen (e.g., Dallas, Atlanta, Seattle, London, Dublin, Canberra, Vancouver and Las Vegas). In places where snowfall is common, such as Utica, Detroit, Denver, Ottawa, Montreal, Quebec City, Chicago, Syracuse, Buffalo, Columbus, Pittsburgh, Toronto and Minneapolis, such small snowfalls are rarely disruptive, because of effective snow and ice removal by municipalities, greater usage of snow tires and drivers more used to winter conditions. Snowfalls in excess of 6 in (15 cm) are usually universally disruptive.

A massive snowstorm with strong winds and other conditions meeting certain criteria is known as a blizzard. A large number of heavy snowstorms, some of which were blizzards, occurred in the United States during 1888 and 1947 as well as the early and mid-1990s. The snowfall of 1947 exceeded two feet with drifts and snow piles from plowing that reached twelve feet and for months, temperatures did not rise high enough to melt the snow. The 1993 "Superstorm" was manifest as a blizzard in most of the affected area.

Large snowstorms could be quite dangerous: a 6 in. (15 cm.) snowstorm will make some unplowed roads impassable, and it is possible for automobiles to get stuck in the snow. Snowstorms exceeding 12 in (30 cm) especially in southern or generally warm climates will cave the roofs of some homes and cause the loss of power. Standing dead trees can also be brought down by the weight of the snow, especially if it is wet or very dense. Even a few inches of dry snow can form drifts many feet high under windy conditions.

Dangers of Snow

Snowstorms are usually considered less dangerous than ice storms. However, the snow can bring secondary dangers. Mountain snowstorms can produce cornices and avalanches. An additional danger, following a snowy winter, is spring flooding if the snow melts suddenly due to a dramatic rise in air temperature. Deaths can occur from hypothermia, infections brought on by frostbite or car accidents due to slippery roads. Fires and carbon monoxide poisoning can occur after a storm causes a power outage. Large amounts of snow can also significantly reduce visibility in the area, a phenomenon known as a whiteout; this can be very dangerous to those who are in a densely populated area, as the whiteout can cause major accidents on the road or while flying. There is also several cases of heart attacks caused by overexertion while shoveling heavy wet snow. It is difficult to predict what form this precipitation will take, and it may alternate between rain and snow. Therefore, weather forecasters just predict a "wintry mix". Usually, this type of precipitation occurs at temperatures between -2 °C and 2 °C (27 °F and 36 °F).

A blizzard is a severe snowstorm or winter storms characterized by low temperature, strong winds, and heavy snow. The difference between a blizzard and a snow storm is the strength of the wind. To be a considered a blizzard, the storm must have winds in excess of 35 miles per hour, it should reduce the visibility to 1/4 miles, and must last for a prolonged period of 3 hours or more. Ground blizzards require high winds to stir up snow that has already fallen, rather than fresh snowfall. Blizzards have a negative impact on local economics and can terminate the visibility in regions where snowfall is rare.

Blizzards can bring near-whiteout conditions, and can paralyze regions for days at a time, particularly where snowfall is unusual or rare. The 1972 Iran blizzard, which caused approximately 4000 deaths, was the deadliest in recorded history.

List of Blizzard Events

• Ground Hog Day Blizzard of 2011
• The New York blizzard in 2010
• Third North American blizzard of 2010
• Second North American blizzard of 2010
• First North American blizzard of 2010
• February 2007 North America Winter Storm
• Saskatchewan blizzard of 2007
• Blizzard of 1999
• Great Blizzard of 1993
• Halloween Blizzard of 1991
• Chicago Blizzard of 1979
• Northeastern United States Blizzard of 1978
• Great Blizzard of 1978
• Blizzard of 1977
• Chicago Blizzard of 1967
• North American blizzard of 1947
• Armistice Day Blizzard of 1940
• Great Lakes Storm of 1913
• Schoolhouse Blizzard of 1888, North American Great Plains
• Great Blizzard of 1888, Northeastern U.S.