Ground frost occurs when the temperature close to the ground (measured 5 cm above the natural ground level) falls to the freezing point or below. This can have certain damaging effects on agriculture and forestry.
Ground frost warnings are only issued during certain times of the year and for low-lying areas (below 600 m):
- North of the Alps between 15 March and 15 June, and between 15 September and 30 November;
- In the south between 15 March and 31 May, and between 1 October and 30 November, with some variability either side, depending on the weather.
Ground frost also occurs in the winter, but since this is not unusual for the season, warnings are not given during the winter period.
|Effects||Frost hazard due to temperatures that cause damage to plants and crops.|
|Behaviour||Take specific protective measures (e.g. covering crops; placing particularly susceptible potted plants against a house wall).|
|Description of measurement and prognostic values||
|Effects||No hazard posed for plants or crops.|
|Description of measurement and prognostic values||Generally no frost, or light localised ground frost.|
*A distinction is made between ‘light to moderate’ and ‘heavy’. Only hazard level 2 exists.