Meteorological Hazards

Term Level Definition Source
Meteorological hazard Subgroup A hazard caused by short-lived, micro- to meso-scale extreme weather and atmospheric conditions that last from minutes to days. IRDR
Extreme temperature Type A general term for temperature variations above (extreme heat) or below (extreme cold) normal conditions. IRDR
Cold wave Subtype A period of abnormally cold weather. Typically, a cold wave lasts for two or more days and may be aggravated by high winds. The exact temperature criteria for what constitutes a cold wave may vary by location. EM-DAT
Heat wave Subtype A period of abnormally hot and/or unusually humid weather. Typically, a heat wave lasts for two or more days. The exact temperature criteria for what constitutes a heat wave may vary by location. EM-DAT
Severe winter conditions Subtype Damage caused by snow and ice. Winter damage refers to damage to buildings, infrastructure, traffic (esp. navigation) inflicted by snow and ice in the form of snow pressure, freezing rain, frozen waterways etc. EM-DAT
Fog Type Subtype Water droplets that are suspended in the air near the Earth’s surface. Fog is, in fact, simply a cloud that is in contact with the ground. IRDR1
Storm Type Subtype (General)
Derecho Subtype Widespread and usually fast-moving windstorms associated with a convection/convective storm. Derechos include downburst and straight-line winds. The damage from derechos is often confused with the damage from tornadoes. IRDR
Hail Subtype Solid precipitation in the form of irregular pellets or balls of ice more than 5 mm in diameter. IRDR
Lightning / Thunderstorms Subtype A high-voltage, visible electrical discharge produced by a thunderstorm and followed by the sound of thunder. IRDR2
Sand/Dust storm Subtype Strong winds carrying particles of sand aloft, but generally confined to less than 50 feet (15 m), especially common in arid and semi-arid environments. A dust storm is also characterized by strong winds but carries smaller particles of dust rather than sand over an extensive area. IRDR
Storm surge Subtype An abnormal rise in sea level generated by a tropical cyclone or other intense types of storm. IRDR
Tornado Subtype A violently rotating column of air that reaches the ground or open water (waterspout). IRDR
Winter storm/Blizzard Subtype A low-pressure system in winter months with significant accumulations of snow, freezing rain, sleet, or ice. A blizzard is a severe snowstorm with winds exceeding 35 mph (56 km/h) for three or more hours, producing reduced visibility (less than 0.25 miles (400 m)). IRDR
Extra-tropical storm Subtype A type of low-pressure cyclonic system in the middle and high latitudes (also called a mid-latitude cyclone) that primarily gets its energy from the horizontal temperature contrasts (fronts) in the atmosphere. When associated with cold fronts, extra-tropical cyclones may be particularly damaging (e.g., European winter/windstorm, or Nor’easter). IRDR
Tropical cyclone Subtype A tropical cyclone originates over tropical or subtropical waters. It is characterized by a warm-core, non-frontal synoptic-scale cyclone with a low-pressure center, spiral rain bands and strong winds. Depending on their location, tropical cyclones are referred to as hurricanes (Atlantic, Northeast Pacific), typhoons (Northwest Pacific), or cyclones (South Pacific and Indian Ocean). IRDR
Severe weather Subtype

  1. Note: the only “Fog” entry in EM-DAT is the Great London SMOG, 1952, which was also accompanied by air pollution. ↩︎

  2. The “Lightning/Thunderstorm” definition corresponds to the definition of “Lightning” in the IRDR glossary. ↩︎