Weather Warning Index

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When severe weather threatens, Environment and Climate Change Canada issues public alert bulletins so that those in affected areas can take steps to protect themselves and their property from harm. Each year, the Meteorological Service of Canada issues, on average, 15 000 severe weather warnings. A weather warning is an urgent message that severe weather is either occurring or will occur. Warnings are usually issued 6 to 24 hours in advance, although some severe weather (such as thunderstorms) can occur rapidly, with less than a half hour's notice.

The Weather Warning Index was created to track the performance of Environment and Climate Change Canada's severe weather warning system in providing Canadians with warnings in sufficient lead time.

Weather Warning Index and individual components for a three-year moving average, Canada, 2009–2011 to 2012–2014

Line chart

Long description

The chart shows weather warning index component scores for the four three-year moving averages available, by warning type: wind, freezing rain, rain, marine gale, snow and severe thunderstorm. The overall index score for each three-year moving average is also provided. The overall score of the index increased from 7.6 to 8.3 between 2009–2011 and 2012–2014. With the exception of marine gale, the score of individual components of the indicator also increased during this period.

Data for this chart
Weather Warning Index and individual components for a three-year moving average, Canada, 2009–2011 to 2012–2014
Warning type2009–2011 score2010–2012 score2011–2013 score2012–2014 score
Freezing rain7.
Marine gale8.
Severe thunderstorm4.
Overall score7.

Download data file (Excel/CSV; 1009 B)

How this indicator was calculated

Note: The index reaches 10 if all extreme weather events in targeted areas were preceded by a warning with sufficient lead time, as per the weather warning performance targets. The overall index and its components are expected to exhibit modest fluctuations due to year to year changes in the predominant weather patterns.
Source: Environment and Climate Change Canada (2015) Meteorological Service of Canada – Integrated Planning and Performance Management Division.

The index is calculated based on information from six warning types that are representative of Canada’s climate. These warning types are severe thunderstorm, rainfall, freezing rain, wind, snowfall and marine gale. For each warning type, a component score is determined based on the warning's accuracy in predicting an actual severe weather event and its timeliness in comparison to the lead times identified within Environment and Climate Change Canada warning performance targets.

The index components are calculated using warnings data from a set of selected geographical regions considered representative of the Canadian climate and for which Environment and Climate Change Canada has sufficient warning events information.

The components are an indication of Environment and Climate Change Canada's performance in providing timely and accurate warnings for each warning type. For instance, the score for severe thunderstorm highlights the challenge of forecasting severe thunderstorms in a timely and accurate manner when compared to other types of severe weather.

Environment and Climate Change Canada's national weather forecast and warning system relies on several observation networks to detect changes in the atmosphere and the development of threatening conditions. The monitoring infrastructure runs 24 hours a day, 7 days a week, 365 days a year. It includes 31 weather radar stations, over 80 lightning detection sensors, approximately 1580 surface weather and climate stations, 46 weather buoys, 53 automated ship observation programs and 31 stations for launching balloon-borne observations of the upper atmosphere. Also extremely valuable to Environment and Climate Change Canada are hundreds of volunteer weather observers and severe weather watchers from coast to coast.

Weather warnings are invaluable for the protection of life and property. They are also critical to provincial and municipal emergency measure organizations (for managing flood control, sewer overflow and stormwater run-off) and for weather-sensitive users (such as snow removal operators and outdoor recreational enthusiasts).

Related information

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