sea ice · Finland / Sweden
Gulf of Bothnia, Baltic Sea
Annual maximum ice cover
Modelled demonstration series · not observed data
Baltic ice records are among the longest continuous environmental series in the world, kept because shipping needed them. Less ice sounds like straightforwardly good news for navigation, and for shipping it is. For the ringed seals that need stable landfast ice to raise pups, it is the opposite.
75 years, modelled
Same reading, two normals
| Normal | Mean | σ | Pct | Return |
|---|---|---|---|---|
| 1951–1980 | 155 thousand km² | −1.50σ | 7th | 1 in 15 years |
| 1991–2020 | 119 thousand km² | −1.07σ | 14th | 1 in 7.0 years |
Today would rank 10 of 76 for lowest value in the modelled series. Nothing about the reading changes between rows — only the yardstick.
The season here
The Baltic freezes from the north down. Maximum ice cover is reached in late February or March and varies hugely between winters.
Where this series comes from
MODELLED SERIES — not observed. Parameters set from published Baltic maximum ice extent climatology. The 75 annual values are synthesised by the seeded generator.
Every number on this page comes from a modelled series: 75 annual values synthesised by a seeded generator from published climatological parameters for Gulf of Bothnia, Baltic Sea. It shows how anomaly reasoning works. It is not a measurement and must not be cited as one.
How to read σ
σ counts standard deviations from this place's own normal. The sigma guide · return periods.
More sea ice stations
Open Gulf of Bothnia on the field →