Climate
| Climate | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
| Daily highs °C | 5 | 6 | 10 | 13 | 18 | 20 | 23 | 23 | 19 | 14 | 9 | 6 |
| Nightly lows °C | 0 | 0 | 2 | 4 | 8 | 11 | 13 | 13 | 10 | 7 | 3 | 1 |
| Precipitation mm | 60 | 51 | 60 | 46 | 64 | 74 | 67 | 58 | 60 | 63 | 66 | 70 |
| Climate in Heerlen |
Roman era
History
Eventhough there have been traces of earlier civilazation the real history of this town starts in the roman era. These erected 2000 years ago a military settlement who they gave the name Coriovallum. This settlement came because of the crossroads from Boulonge-Köln and Xanten-Aachen-Trier.