I noticed some funny stuff on the maps plotted at the weather map site. Non-fitting temperatures like 28°C in the south of the Netherlands where it is -4°C to -8°C according to the people who know. Or 5°C at site 'EHDV' which was plotted somewhere in the eastern part of the country, near Marknesse, but the reading for Marknesse was not the same.
The first error was caused by the recent upgrade at home: Ubuntu comes with Geo::METAR 1.14. I did not notice this right away because they did fix the error about only accepting metar data from the USA. So I put in my own Geo::METAR which fixes the parsing. The other error was that EHDV was in the wrong location in my data. Searching using google found that EHDV is the code for oil platform D15-FA-1 which is also hard to find, but somewhere deep in the data history of air traffic control the Netherlands is the right location out on the North Sea. Where it is indeed a lot warmer than in the east of the country, thanks to less cold wind from the east and more warm wather from the Gulf stream.