Ice season in the Baltic Sea

The Baltic Sea ice season starts when the first ice has formed and ends when the last ice has melted, usually the first ice forms around November and the last remains melt in April or May. But the timeframe can vary from year to year depending on the weather conditions. The table below lists the ice statistics of each year since 1991, including: when the first ice formed, the maximum ice extent, the date of reaching the maximum ice extent and additionally the length of the ice season. The list is based on the Finnish Meterological Institute's data, which is made in collaboration with SMHI.

Yearly statistics of Sea Ice seasons 1991-2025

Year	First ice formation	Length of the season	Maximum ice extent (km2)	Date of maximum extent
1990/1991	-	-	126 000	-
1991/1992	-	-	74 000	-
1992/1993	-	-	98 000	-
1993/1994	-	-	221 000	-
1994/1995	-	-	76 000	-
1995/1996	-	-	265 000	-
1996/1997	mid November	Longer than usual	265 000	February 18
1997/1998	late October	about normal	130 000	March 18
1998/1999	early November	about normal	157 000	February 11
1999/2000	late November	a little bit shorter than usual	95 000	February 24
2000/2001	late November	shorter than usual	129 000	March 26
2001/2002	early November	a little bit shorter than usual	102 000	February 1
2002/2003	late October	longer than usual	233 000	March 5
2003/2004	late November	about normal	153 000	March 11
2004/2005	mid November	shorter than usual	178 000	March 16
2005/2006	early December	about normal	211 000	March 16
2006/2007	early November	shorter than usual	140 000	February 23
2007/2008	mid November	much shorter than usual	49 000	March 24
2008/2009	mid to late November	shorter than usual	110 000	February 20
2009/2010	early November	about normal to slightly longer	244 000	February 17
2010/2011	mid November	longer than usual	309 000	February 25
2011/2012	early December	much shorter than usual	179 000	February 11
2012/2013	late November	about normal	177 000	March 15
2013/2014	late November	shorter than usual	100 000	February 7
2014/2015	mid November	shorter than usual	51 000	January 23
2015/2016	late November	shorter than usual	110 000	January 22
2016/2017	late November	about normal	101 000	February 12
2017/2018	early November	about normal	175 000	March 5
2018/2019	early December	shorter than usual	88 000	January 27
2019/2020	early December	much shorter than usual	37 000	March 5
2020/2021	mid November	shorter than usual	127 000	February 15
2021/2022	late October	longer than usual	93 000	February 4
2022/2023	early December	a little bit shorter	81 000	March 12
2023/2024	late October	longer than usual	135 000	February 12
2024/2025	early November	shorter than usual	85 000	February 20

References

• Sea Ice Statistics - Finnish Meteorological Institute (Finnish Meterological Institute's data on sea ice statistics).
• Seinä, A.; Peltola, J. (1991). "Jäätalven kestoaika ja kiintojään paksuustilastoja merialjää 1961-1990" [Duration of the ice season and statistics of fast ice thickness along the Finnish coast 1961-1990]. Finnish Marine Research (in Finnish) (258). hdl:10138/167792. ISSN 0357-1076.
• Leppäranta, Matti (2012). "Ice Season in the Baltic Sea and Its Climatic Variability". From the Earth's Core to Outer Space. Lecture Notes in Earth Sciences. Vol. 137. Berlin, Heidelberg: Springer Berlin Heidelberg. pp. 139–149. doi:10.1007/978-3-642-25550-2_9. ISBN 978-3-642-25549-6. Retrieved 2025-07-14.