Bewolking — 2020
| Month | Harlingen | Vlieland | Difference |
|---|---|---|---|
| Jan | 81.5 % | 81.2 % | +0.3 |
| Feb | 71.9 % | 72.1 % | -0.2 |
| Mar | 48.3 % | 47.8 % | +0.5 |
| Apr | 45.4 % | 45.7 % | -0.3 |
| May | 45 % | 44.6 % | +0.4 |
| Jun | 65.7 % | 65 % | +0.7 |
| Jul | 61.6 % | 61.9 % | -0.3 |
| Aug |
| – |
| – |
| – |
| Sep | – | – | – |
| Oct | – | – | – |
| Nov | – | – | – |
| Dec | – | – | – |