Squall
A squall is an atmospheric phenomenon characterised by a very large variation of wind speed: it begins suddenly, has a duration of the order of minutes and decreases suddenly in speed. It is often accompanied by a shower or thunderstorm (WMO, 2018).
Primary reference(s)
WMO, 2018. Manual on Codes, International Codes, Volume I.2. WMO-No. 306. World Meteorological Organization (WMO). Accessed 16 May 2025.
Annotations
Additional scientific description
The National Oceanic and Atmospheric Administration (NOAA) National Weather Service describes a squall as follows (NOAA, 2019):
- A strong wind characterised by a sudden onset in which the wind speed increases to at least 16 knots and is sustained at 22 knots or more for at least one minute.
- In nautical use, a severe local storm considered as a whole, that is, winds, cloud mass and (if any) precipitation, thunder and lightning.
The American Meteorological Society describes a squall as follows (AMS, 2012):
- A strong wind characterised by a sudden onset, a duration of the order of minutes, and then a sudden decrease in speed. In U.S. observational practice, a squall is reported only if a wind speed of 16 knots or more is sustained for at least two minutes (thereby distinguishing it from a gust).
- In nautical use, a severe local storm considered as a whole, that is, winds and cloud mass and (if any) precipitation, thunder and lightning.
Metrics and numeric limits
Not available.
Key relevant UN convention / multilateral treaty
Sendai Framework for Disaster Risk Reduction 2015-2030.
Drivers
Squalls occur during thunderstorms.
Impacts
Squalls are sudden changes in wind conditions. In general, a squall may not be very strong and may only last for a short time. However, owing to their unpredictability and sudden arrival, squalls pose a threat to marine operations that require a fairly calm sea state (Lu et al., 2018).
Human health can be severely affected by wind-related hazards such as squalls and windstorms. Direct effects occur during the impact phase of a storm, causing death and injury due to the force of the wind. Becoming airborne, being struck by flying debris or falling trees and road traffic accidents are the main dangers. Indirect effects, occurring during the pre- and post-impact phases of the storm, include falls, lacerations and puncture wounds, and occur when preparing for, or cleaning up after a storm. Power outages are a key issue and can lead to electrocution, fires and burns and carbon monoxide poisoning (CH0302) from gasoline powered electrical generators. In addition, worsening of chronic illnesses due to lack of access to medical care or medication can occur. Other health impacts include infections and insect bites (Goldman et al., 2014).
Multi-hazard context
The figure below summarises common interactions between squalls and other hazards. This information should be used with caution and not be solely relied upon in Disaster Risk Management, particularly as some interactions may not have been included. Note that hazardous events occurring together or locally in space or time may not necessarily cause, amplify, or be otherwise related to each other. Specific examples of multi-hazard context can be found in the ‘Hazard drivers’ and ‘Impacts’ sections above.
Multi-hazard diagram
Risk Management
No Information Available
Monitoring
The section above and the table below offer an overview of monitoring tornadoes. This information can be used for forecasting within a national early warning system (EWS). Since EWS capacities and processes differ across countries, the most current and specific information regarding EWS should be obtained from the appropriate national or regional agency/authority responsible for disaster management.
| Which institution(s) produce(s) Disaster Risk Data/Information? |
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| How is the Hazard Observed/Monitored/Forecast? | Squalls are monitored using Doppler radar, weather satellites, and other remote sensing technologies that track cloud formations, wind patterns, and lightning activity. Meteorologists assess atmospheric conditions, including temperature, humidity, and wind shear, to predict the development and intensity of squalls. By integrating advanced numerical weather models with real-time observational data, forecasters can improve the accuracy of squall predictions and track their movement. This enables timely warnings to mitigate risks to aviation, infrastructure, and communities from associated hazards such as heavy rainfall, strong winds, lightning, and hail. |
References
American Meteorological Society (AMS), 2012. Glossary of Meteorology: Squall. American Meteorological Society (AMS). Accessed 16 May 2025
Goldman, A., Eggen, B., Golding, B. and Murray, V., 2014. The health impacts of windstorms: a systematic literature review. Public Health, 128, pp.3–28.
Lu, Y., Ozaki, M. and Wada, R., 2018. Squalls in sea off coast of Japan and their effects on marine operations based on weather observatory data at remote islands. Journal of Marine Science and Technology, 23, pp.104–121.
National Oceanic and Atmospheric Administration (NOAA), 2019. National Weather Service Glossary: Squall. National Oceanic and Atmospheric Administration (NOAA). Accessed 16 May 2025.