Changing seasons in Germany
Most discussions about climate change focus on how global temperatures have shifted over the past 50–100 years. But since temperature directly shapes the rhythm of the seasons, an equally fascinating question is: have the seasons themselves changed in length or timing?
Answering this isn’t straightforward, starting with the definition of a “season.” Should we pick an arbitrary temperature threshold? Count days above or below a certain value? Turns out Nature offers a better solution.
Many plants respond consistently to cumulative changes in temperature, humidity, sunlight, and other environmental factors. In that sense, they act like living “batteries” of atmospheric conditions, integrating the weather over time rather than reacting to our arbitrary single-day thresholds. This is the foundation of phenology, a branch of agrometeorology that tracks recurring biological events such as leaf-out, flowering, and fruiting to mark seasonal transitions.
The DWD maintains one of the world’s largest and most detailed phenological records, and remarkably, much of it is openly accessible (THANK YOU). Using this dataset, I analyzed seasonal markers from a variety of plant species across Germany from 1955 to 2025, averaging observations from many reporting stations.
The resulting picture is striking. Once we smooth out year-to-year variability (black lines), clear patterns emerge. Winter is shrinking, largely because the onset of early spring has been shifting earlier. Spring and autumn are expanding, with the change most pronounced in spring.
Summer isn’t lengthening—instead, it’s simply moving earlier in the calendar.