The Forecast Significance Index is a scale from 0-100 that gives one an idea or measure of the severity or uniqueness of the overall forecast, or individual aspects like temperature, precipitation and wind forecast values when compared to the long-term climate average value. The lower the value, the less significant the forecast value is compared to the long-term climate mean. So, for example, a value of 90 for the temperature forecast indicates that the forecast value is uniquely high (or low) depending on the season. Likewise a high value for wind indicates a significant wind event (when compared to the long-term average) is most likely going to occur for your location.