A new scoring index is proposed for the verification of the Canadian weather warning program. Called weather warning index (WWI), the new measure is designed to be sensitive to two attributes of warnings, their timeliness and accuracy, and to summarize the verification information into a single value for a representative set of regions of Canada and for several weather elements for which warnings are issued. Given the opposing nature of the two attributes (long lead times are likely to be associated with lower accuracy), it was necessary to carefully balance the score to keep it proper in a general sense. The design decisions for the WWI are presented and discussed, and the score computation is illustrated with sensitivity experiments using 3 years of warning forecasts and observations. Copyright © 2013 Royal Meteorological Society