Evolution of warm nights in the Canary Islands (1950–2023): evidence for climate change in the Southeastern North Atlantic

Nighttime temperatures have a direct impact on the health and well-being of the population, and are closely linked to the aggravation of certain pathologies and mortality. As global warming acquires extraordinary magnitudes, concepts such as warm night, tropical night or equatorial night, used as indicators to evaluate the evolution of temperatures during the night, are becoming popular. This paper analyses the evolution of nighttime temperatures in the Canary Islands since 1950, identifying a very notable increase in the daily minimum temperature, particularly at the summits, where the rate of increase exceeds 0.2 °C per decade. Overall, the daily minimum temperature easily reaches 20 °C in many parts of the islands, with a statistically significant upward trend in the frequency of tropical nights. In addition, they tend to occur over an increasingly longer season, more consecutively and with greater thermal intensity. Equatorial nights — ≥ 25 °C— are still an eminently summer phenomenon of growing importance in certain areas of the inland of some islands. Torrid nights — ≥ 30 °C—, on the other hand, are associated with extremely warm episodes that affect specific sectors conditioned by local factors.