Variability of North American Wind Chill Temperatures

Wind chill temperature (WCT) is a measure related to the human perception of cold and is an impact-relevant method to evaluate the severity of winter weather, as it effects human health. Therefore, WCT has the potential to provide important insight into the fluctuations of winter weather as it relates to climate change since it is derived from both wind speed and air temperature conditions. The spatial and temporal variations of WCT have seen very narrow examination with only a small number of studies, having limited scope and often focused on a specific region or location in the Arctic, Europe, Asia, South America, and North America.

The current study presents an investigation to understand the spatial and temporal variations of mean, severe, and extreme WCTs across North America by exploring intra-seasonal and inter-decadal changes using hourly surface measurements for the winters (December‒February) from January 1970 through February 2014. Monthly analyses of WCT showed that January had (a) the coldest mean WCTs across most of North America, (b) the most extreme WCTs, as identified by the coldest 1% of the WCT frequency distribution at each station, and (c) the greatest temporal frequency of severe WCTs that were ≤ -32 °C. The most extreme WCTs were most often located in the Hudson Bay Region, while north central and northeastern North America experienced the largest monthly changes in WCT during the winter season. Analyses of decadal WCTs found that across many regions of North America (a) mean WCTs are warming due to both a warming of mean temperature and a decreasing of mean wind speeds, (b) extreme WCTs are warming with a greater magnitude than the mean WCTs, and (c) the frequency of severe WCTs (≤ -32 °C WCTs) is decreasing.