The predominant wind direction in the Netherlands is southwest, which causes a moderate maritime climate, with warm summers and cool winters, and typically high humidity. This is especially true close to the Dutch coastline, where the difference in temperature between summer and winter, as well as between day and night is noticeably smaller than it is in the southeast of the country.
Ice days (maximum temperature below 0 °C (32 °F)) usually occur from December until February, with the occasional rare ice day prior to or after that period. Freezing days (minimum temperature below 0 °C (32 °F)) occur much more often, usually ranging from mid-November to late March, but not rarely measured as early as mid-October and as late as mid-May. If one chooses the height of measurement to be 10 cm (4 in) above ground instead of 150 cm (59 in), one may even find such temperatures in the middle of the summer. On average, snow can occur from November to April, but sometimes occurs in May or October too.
Warm days (maximum temperature above 20 °C (68 °F)) in De Bilt are usually found in April to October, but in some parts of the country these warm days can also occur in March, or even sometimes in November or February (usually not in De Bilt, however). Summer days (maximum temperature above 25 °C (77 °F)) are usually measured in De Bilt from May until September, tropical days (maximum temperature above 30 °C (86 °F)) are rare and usually occur only in June to August.
Precipitation throughout the year is distributed relatively equally each month. Summer and autumn months tend to gather a little more precipitation than the other months, mainly because of the intensity of the rainfall rather than the frequency of rain days (this is especially the case in summer, when lightning is also much more frequent).
The number of sunshine hours is affected by the fact that because of the geographical latitude, the length of the days varies between barely eight hours in December and nearly 17 hours in June.