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.
Danger levels frost
Ground frost warnings are only issued between 15 March and 31 October and for low-lying areas (below 600 m). Ground frost also occurs in the winter, but since this is not unusual for the season, warnings are not given during the winter period.
Danger level 1 (minimal or no danger)
Impact
No hazard posed for plants or crops.
Recommended action
-
Description of measurement and prognostic values
Generally no frost, or light localised ground frost.
Danger level 2 (moderate danger)
Impact
Frost hazard due to temperatures that cause damage to plants and crops.
Recommended action
Take specific protective measures (e.g. covering crops; placing particularly suscepti-ble potted plants against a house wall).
Description of measurement and prognostic values
- Light to moderate ground frost at temperatures between 0° and -4° (at a height of 5 cm above ground level).*
- Heavy ground frost at temperatures below -4° at a height of 5 cm above ground level.*
Danger level 3 (significant danger)
Ground frost warnings are only issued in level 2.
Danger level 4 (severe danger)
Ground frost warnings are only issued in level 2.
Danger level 5 (very severe danger)
Ground frost warnings are only issued in level 2.
Notes:
*A distinction is made between ‘light to moderate’ and ‘heavy’. Only hazard level 2 exists.