Impact of Daylight Saving Time on Nighttime Temperatures and Heatwaves in France

Paris – 25.06.2026: Since the 1970s, France has adjusted clocks forward by one hour twice a year to make better use of daylight and reduce energy consumption. This practice extends evening hours during summer but results in increased energy usage and influences nighttime temperatures. Given the growing frequency and intensity of heatwaves, experts are debating whether abolishing daylight saving time could lead to cooler nights and improved coping with these extreme weather events.

According to Météo-France, heatwaves have become more frequent and intense in recent decades. Since 1947, 49 heatwaves have been recorded in France, 32 of which occurred after 2000. This increase is clearly attributable to climate change. Particularly problematic are the so-called “hot nights,” where temperatures do not drop below 20 degrees Celsius at night. Such nights heavily strain the human body and disrupt sleep. These nights are increasingly observed especially in urban areas and along the coast.

Daylight saving time was originally introduced to reduce energy consumption by utilizing longer daylight hours. However, its impact has significantly diminished over time and today accounts for less than 0.3 percent of the national CO2 emissions. Abolishing daylight saving time could lead to earlier sunsets, which theoretically might bring cooler nights. The actual effects on nighttime temperatures, however, are complex and depend on factors including geographic location, urban heat effects, and climatic conditions. A simple return to standard time would therefore not automatically result in significant cooling.

Similarly, the influence of daylight saving time on the occurrence and intensity of heatwaves is minimal. These extreme weather patterns are mainly driven by large-scale meteorological processes and climate change. The time change has only a marginal effect in this regard.

Given the limited impact of daylight saving time on nighttime temperatures and heatwaves, adaptation measures to climate change should be the primary focus. These include improving building energy efficiency, promoting urban green spaces, and advancing early warning systems for extreme weather events. Such measures can help manage the negative consequences of heatwaves more effectively.

In summary, abolishing daylight saving time alone does not provide a sufficient solution to the challenges posed by heatwaves in France. A comprehensive approach that includes both preventive and adaptive strategies is necessary to sustainably counteract the impacts of climate change.