Winter wonderland

This is Hans, a software engineer at Datawrapper, and the person who works a lot on our locator map feature. For this week’s edition of the Weekly Chart, I wanted to answer a question I had asked myself lately: “When did we have snow for the last time?”

I can’t recall the last time Berlin was covered in snow. Last winter, there was none – well, expect some snowflakes for about one hour around March. The winter before, I remember a day where it was possible to go sledding for a few hours in the morning on a thin layer of snow. But I also remember winters with lots of snow. When was that? I went on a quest to find out.

The table shows all the weather stations in Germany from the German Meteorological Service (DWD) where snow cover data was available and complete. I added four columns, showing when snow cover was 1-2 cm, 3-5 cm, 6 – 10 cm, and more than 11 cm for the last time (the data is only recorded in rounded numbers). To make it easier for the viewer to read how many years have passed, I added a colored background to the date fields and added a color key to explain the colors. I also added a small column chart to the right side of the table (desktop only) for a quick overview of the maximum snow cover from the last 20 years.

The columns can be sorted by click on the header row, which allowed me to get quick insights: Wolfsburg and Hannover haven’t had any snow cover at all for the last two years, while the Zugspitze is already covered with snow these days. 59 out of the 125 stations haven’t recorded any snow higher than 10 cm for the last three years. Worms and Bremen haven’t seen any high snow cover for the last ten years. And as the column chart shows us, 2010 was the last year with lots of snow everywhere.

And what about my home town, Berlin? The search field also allowed me to quickly find the weather stations in Berlin. And indeed, there was no snow last winter. In the inner city of Berlin, the last 10cm snow cover was six years ago. My memory served me right for the recent years. It’s quite sad to see that we haven’t had lots of snow for six winters. Even with global warming, there might be another white winter in the coming years – but those winters will certainly not occur that often again.

From data to table

The go-to place for meteorological data in Germany is the open data portal from the German Meteorological Service (DWD). Here I downloaded the data from all weather stations. I wrote a script to download all the historical and recent data. Then I filtered the data to keep only the station with full coverage between October-April (the months where snow cover is recorded) and no errors between the year 2000 and 2020. Last but not least, I parsed the data so that it can be displayed in the table.

Tips to use this table

The chart gets updated once a day. If you want to use it for a local newspaper, hover over the table and click “Edit this chart”, then publish it. Add ?search= plus the city/state you want to filter for to the end of the URL to only show the stations that match your search. Like so:

That’s it from me for this week. If you want to learn more about snow in Germany, visit this interactive poster by the great team from the Berliner Morgenpost, showing when there was a white Christmas in cities in Germany. Their project served as an inspiration for this Weekly Chart. Also, do let me know if you have feedback, suggestions or questions. I am looking forward to hearing from you on Twitter. We’ll see you next week!