Weather variables information
Temperature (2m) and relative humidity (2m):
Comparable to measurements at 2 meters above ground.
Atmospheric air pressure adjusted to mean sea level as most commonly used for weather reports. The local pressure varies with altitude. Locations at higher elevation have a lower local atmospheric pressure.
Total precipitation amount including rain, convective precipitation and snow. 1 mm at 10:00 is comparable to a rain-gauge measurement from 9:00-10:00.
Fraction of total precipitation that falls as snow and is converted to cm instead of mm.
Total cloud cover:
Percentage of the sky covered with clouds: 50% means half of the sky is covered. 0-25% is mostly clear sky, 25-50% partly cloudy, 50-85% mostly cloudy and above 85% overcast.
Low, mid, high cloud cover:
Cloud cover at different altitudes. High clouds (8-15 km) like Cirrus, are less significant for total cloud cover than mid clouds (4-8 km) like Alto-Cumulus and Alto-Stratus, or low clouds (below 4 km), like Stratus, Cumulus and fog.
Global radiation (diffuse and direct) on a horizontal plain given in Watt per square meter.
Hourly average wind speeds at given altitude levels (e.g. 10 and 80 meters above ground) or pressure level (e.g. 900 hPa). Units can be selected.
Wind direction in degrees, seamlessly from 0° (wind blowing from North), 90° (East wind), 180° (South wind) and 270° (West wind) to 359°.
Short term wind speed turbulence in an hour. Gusts are maximum measurable wind speed and indicate the level of turbulence. They are mostly higher than regular wind speeds.
Please note: the dataset between 1940 and 1980 might have lower accuracy than the data from 1980 onwards due to the absence of satellite data.
All data will use the selected timezone. There is no automatic switching for daylight saving time. Data are either summer or winter-time. The current timezone is selected automatically. We highly recommend GMT+00 for further processing.
Aggregate data to daily minimum, mean, maximum and summation in CSV download. This simplifies further data analyses in external programs.
Parameter for growing degree days (GDD)
Adjust base and limit parameter for growing degree calculation. A limit-value lower than base, calculates the temperature cold sum.