Bewolking — 2020
| Month | Heerlen | Brunssum | Difference |
|---|---|---|---|
| Jan | 72.7 % | 72.7 % | +0.0 |
| Feb | 76.8 % | 76.8 % | +0.0 |
| Mar | 54.6 % | 54.6 % | +0.0 |
| Apr | 31.8 % | 31.8 % | +0.0 |
| May | 50.2 % | 50.2 % | +0.0 |
| Jun | 63.1 % | 63.1 % | +0.0 |
| Jul | 61.7 % | 61.7 % | +0.0 |
| Aug |
| – |
| – |
| – |
| Sep | – | – | – |
| Oct | – | – | – |
| Nov | – | – | – |
| Dec | – | – | – |