Changes in daily and nightly day-to-day temperature variability during the twentieth century for two stations in Switzerland

Abstract

Summary An analysis of day-to-day variability was performed on two century-long daily minimum and maximum temperature series from Switzerland. Warmer temperatures during the 20 th century have been accompanied by a reduction in dayto-day variability, particularly for minimum temperatures and for winter. There is a significant negative correlation between day-to-day variability and the skewness of the temperature distribution, particularly in winter and for minimum temperatures. Lower variability is linked to a reduced number of cold days and nights. Higher NAO index values tend to be associated not only with warmer temperatures but also with lower day-to-day variability. This paper confirms that the temperature warming during the 20 th century has happened mainly through the loss of the coldest part of the series, not only in the 24-hour or yearly cycle, but also through the loss of the coldest episodes in each month.