Rise in Tropical Nights in Sweden Linked to Health Risks

Sweden is witnessing an alarming increase in the frequency of tropical nights—nights when temperatures do not drop below 20 degrees Celsius. According to recent analyses, tropical nights have become over three times more common than in previous decades. In 2023 alone, Sweden has already recorded 19 tropical nights, marking a significant rise from the average of 9 tropical nights per year noted at least one measurement station over the past decade. This is in stark contrast to the average of only 2.5 tropical nights per year from 1961 to 1990.

These warm nights predominantly occur during late summer when water bodies are at their warmest. While many might struggle to sleep through these hot evenings, health experts warn of severe health implications. Heart specialist Petter Ljungman from Karolinska Institute cautioned that elevated nighttime temperatures can lead to increased risks of mortality and strokes, as evidenced by studies from various urban areas including Barcelona and London. This rising trend in tropical nights not only reflects changing climate patterns but also signals a need for public awareness about the associated health risks tied to prolonged exposure to high minimum temperatures.