Trends in Extreme Non-Winter Wind Chill Temperatures in Alaska & Western Canada

Wind chill temperature (WCT) is a derived value that uses surface wind speeds and air temperature to convey what the temperature feels like in cold/windy conditions. An examination of wind chill temperature can provide useful insight into how regional climate is changing from one location to another and the parameters that may be undergoing substantial changes. The current study aims to understand the trends in the spatial and temporal variations of non-winter extreme WCTs across Alaska and Western Canada during a 40-year time period (1980-2019) using hourly surface weather observations from 29 station locations. Non-winter months are defined as months other than December, January, or February. Extreme WCTs were evaluated as the coldest 1% of winter WCTs at each surface location. During the 40-year period, non-winter extreme WCTs primarily occurred in March and November. These occurrences represented 99.8% of non-winter extreme WCTs (i.e., 43.4% in March and 56.5% in November) and comprised 1,740 hourly observations from stations across the region. The majority of non-winter extreme WCTs occurred in southwestern British Columbia and the northernmost regions of Alaska and western Canada. Very few non-winter extreme WCTs occurred in south-central Alaska, Manitoba, and Saskatchewan. The few stations with increases in the number of hours of non-winter extreme WCTs from the first 20 years to the most recent 20 years occurred in the eastern portion of the region, whereas more stations experienced a large decrease in the number of hours of non-winter extreme WCTs in the western portion of the region.