Since 1960, the onset of winter in Spain has been delayed by over a week, while its conclusion has advanced by up to three weeks, as revealed by an analysis from eltiempo.es regarding the duration of this season. The analysis highlights that winter in the northern hemisphere is set to commence on 22 December at 4:27 hours peninsular time. In the Canary Islands, particularly in lower regions like Tenerife or Gran Canaria, the shortening of winter is more pronounced, whereas in higher areas like Izaña, the reduction is less, with a decrease of 6 days.
The study by this digital weather information outlet confirms a general trend of winter shortening. For instance, frosts have lessened across large parts of Spain. Correspondingly, the wintry season is shrinking, encompassing fewer weeks each year.
From the 1960s to the last decade (2011-2020), certain areas, such as Lérida or San Javier in Murcia, have seen winters shortened by over 30 days. In Lérida, the wintry season duration decreased from 149 to 118 days, with the start delayed by over a week and the end advanced by about three weeks.
Many other regions also exhibit significant reductions, ranging from 20 to 30 days. For example, Cuenca’s cold season has shortened by 28 days: starting from 2 November to 18 November, and ending from 8 April to 29 March.
Generally, the interior and east of the country have experienced the most significant reduction in wintry season duration. In contrast, the decrease is somewhat lesser in the south and parts of the northern plateau.
The analysis also traces back to the last century, noting that winters typically began at the end of October or early November. However, over the last two decades, the onset has regularly been delayed to the second half of November. Similarly, the end of winter, which used to be around mid-April, now tends to occur at the end of March.
From a climatic perspective, winter encompasses December, January, and February. The analysis used percentiles to arrange the data from lowest to highest, establishing the 25th percentile of all mean temperatures for 1991-2020 as the threshold for wintry season. The analysis was independently conducted for each season.
The 25th percentile (P25) value is determined first, followed by calculating the average of mean temperatures for each five-day period, considering +/-2 days around the central one. The first date when the average is lower than the P25 marks the beginning of winter, while the last day with an average below the P25 is considered the end of winter.
