The reserve is one of the wettest and coldest parts of Belgium. This region is the lowest, flattest, warmest, and wettest part of the state. The annual average rainfall is , with November being the wettest month. Winters are usually wet and humid, with January being the wettest month. The wettest year was 1983, with of rainfall. Rainfall activity intensifies as the month goes on, leading into wettest month, July. Average annual precipitation is with December being the wettest month with . It is also one of the wettest temperate regions in the northern hemisphere. Most precipitation occurs from November to March with February being the wettest month. Average annual precipitation is , with the wettest month being July, averaging . Three very wet months meant that the winter was the wettest on record. Precipitation varies across the region, with areas adjacent to the coast being the wettest. October is the wettest month with of rain. Yearly precipitation is about , making Ljubljana one of the wettest European capitals. Elsewhere the wet season stretches from May through November, with May being the wettest month.