Neerslag — 2020
| Month | Alphen aan den Rijn | Leiderdorp | Difference |
|---|---|---|---|
| Jan | 47.6 mm | 69.1 mm | -21.5 |
| Feb | 127.7 mm | 126.9 mm | +0.8 |
| Mar | 53 mm | 45.3 mm | +7.7 |
| Apr | 25.3 mm | 25.5 mm | -0.2 |
| May | 20.5 mm | 16.9 mm | +3.6 |
| Jun | 67.6 mm | 64.4 mm | +3.2 |
| Jul | 62.4 mm | 71.2 mm | -8.8 |
| Aug | – | – | – |
| Sep | – | – | – |
| Oct | – | – | – |
| Nov | – | – | – |
| Dec | – | – | – |