Climate data De Bilt; temperature, precipitation, sunshine 1800-2014

Table description


This table presents climate data from the Dutch weather station De Bilt (source: KNMI).
The average winter and summer temperatures, which started in 1800, are the longest current series shown in the table.
The series on the average year temperature and on hours of sunshine per year started in 1900. For the number of days below of above a certain temperature (ice days, summery days) the ranges started between 1940 and 1950. The complete set of climate data is available from 1980 onwards.

Data available from: 1800-2014.

Status of the figures:
All data are definite.

Changes as of 19 April 2016:
Not. This table has been discontinued.

When will new figures be published?
Not applicable anymore.

Data on the weather and climate in The Netherlands can be found on the website of the Royal Netherlands Meteorological Institute KNMI

Description topics

Temperature
Air temperature in degrees Celsius.
Year average
The average of daily recorded temperatures for the whole year.
Winter average
The average of daily recorded temperatures in the winter, i.e. from December to February. The average therefore includes one month of the previous year.
Summer average
The average of daily recorded temperatures in the summer, i.e. June to August
Winter average minimum temperature
The average of the lowest temperature of each day in the winter, i.e. from December to February. The average therefore includes one month of the previous year.
Summer average maximum temperature
The average of the highest temperature of each day in the summer, i.e. from June to August.
Ice days
Number of days in the year with a maximum temperature below 0.0 degrees Celsius
Frost days
Number of days in the year with a minimum temperature below 0.0 degrees Celsius
Summery days
Number of days in the year with a maximum temperature of 25.0 degrees Celsius or higher.
Tropical days
Number of days in the year with a maximum temperature of 30.0 degrees Celsius or higher.
Heating degree days
Heating degree days (HDD):
The sum per year of average daily temperatures below 18 degrees Celsius.
For example:
-a day with an average temperature of 20 degrees Celsius: no HDD
-a day with an average temperature of 10 degrees Celsius: 18-10 = 8 HDD
-a day with an average temperature of -4 degrees Celsius: 18 - (- 4) = 22 HDD
The sum of these three days is thus 30 heating degree days .
Precipitation
Includes rain, snow, hail, sleet, dew and frost.
Quantity of precipitation
The quantity of precipitation per day is the number of mm that falls between 8.00 hrs in the morning and 8.00 hrs the following morning, Measured with a pluviometer.
Days with precipitation
The number of days with at least 1.0 mm precipitation
Snow days
A day on which at least one snow flake has been observed.
Dry days
Day without measurable precipitation.
Days with fog
Days on which visibility is less than 1,000 metres at some time.
Evaporation
Transition of liquid water (in soil and plants) into vapour, Calculated from the average day temperature and solar radiation.
Relative humidity
The ratio of the pressure of water vapour in the atmosphere to the saturated vapour pressure of water at that temperature, measured at a height of 1.5 metres above the ground.
Sunshine
Radiation of the sun (=global radiation). The duration of sunshine is calculated from the global radiation.
Hours of sunshine
The duration of the sunshine in hours. Until 1992 this was measured with a Campbell-Stokes sunshine meter. The instrument consists of a crystal ball, which works as a burning glass. Since 1992 sunshine has been measured electronically with a pyranometer. Values above approximately 120 Watt/m2 are registered as sunshine. This more or less corresponds with a situation in which the sun generates shadows.
Sunless days
Days with zero hours of sunshine.