Warnings on the sea water level

On the basis of the sea water level observations made, the warning limits have been set so that the frequency of warnings at the lowest risk level (yellow) is once a year, at the second risk level (orange) once in five years, and at the highest risk level (red) once in 20 years.

Only one warning level is used for low water (yellow), but all three warning levels are used for high water (yellow, orange and red). The warning levels are set for the 14 observation stations.

Warnings for sea level are drawn up for periods of up to 5 days.

The warning limits are listed in the table below referenced to the theoretical mean water.

Sea level warning limits, theoretical mean water (MW)

very high
dangerously high (red)
Kemi, Oulu -80 cm 115 cm 140 cm 170 cm
Raahe, Pietarsaari -65 cm 85 cm 110 cm 130 cm
Vaasa -50 cm 85 cm 110 cm 130 cm
Kaskinen, Pori, Rauma -50 cm 75 cm 100 cm 120 cm
Föglö -50 cm 65 cm 85 cm 100 cm
Turku, Hanko -50 cm 70 cm 95 cm 110 cm
Helsinki, Porvoo -60 cm 80 cm 115 cm 130 cm
Hamina -70 cm 110 cm 145 cm 170 cm
A man standing in the flood water.
Flooding. Photo: Eija Vallinheimo