Archived Messages

Normals Codes:

Recent modifications have been made to ensure the 1971-2000 Normals codes are displayed correctly as described in Calculation of the 1971 to 2000 Normals for Canada, on Climate Data Online. Due to changes, ALL yearly values and normals codes are now displayed, while previously available elements may no longer be displayed. For more information on Normals codes, please see Calculation of the 1971 to 2000 Normals for Canada.

Wind Chill and Humidex:

As of November 19 2009, changes have been made to how Wind Chill and Humidex values are calculated. Previously, Wind Chill was calculated using an equation that required a wind speed of at least 10 km/h and an ambient air temperature of 0°C or less. This implied that there was no Wind Chill for wind speeds of less than 10 km/h, which is not accurate. As a result, a new equation was introduced for wind speeds greater than 0 km/h but less than 5 km/h, and the wind speed threshold for the original equation was lowered to greater than or equal to 5 km/h. The ambient air temperature threshold of 0°C or less has remained the same for both Wind Chill calculations. These two methods of calculating Wind Chill have also been adopted by the Weatheroffice.

The equation used for the calculation of Humidex has remained the same, however, the value used when converting from Celsius to Kelvins for dew point temperature has changed. Previously, the temperature in K was determined by adding 273.1 to the temperature in degrees C. The value of 273.1 has been changed to 273.16 to ensure greater accuracy.