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The Weather of 2025
Observations at Vellmar, with the level of the Ostra, fog on the river and the state of Lake Tarn at Tarnmund, as recorded by The Tarnmund Observatory, observing since 1869. Temperatures in degrees, rainfall in millimetres.
The months
| Month | Mean | Warmest day | Coldest night | Rain | Fog days | Frost days | Remarks |
|---|---|---|---|---|---|---|---|
| January | -1.9° | 7° | -11° | 35 mm | 5 | 29 | |
| February | -0.6° | 12° | -13° | 36 mm | 4 | 22 | |
| March | 3.7° | 15° | -7° | 45 mm | 3 | 0 | |
| April | 9.0° | 19° | 0° | 55 mm | 2 | 0 | |
| May | 14.3° | 23° | 6° | 79 mm | 2 | 0 | |
| June | 17.6° | 30° | 7° | 98 mm | 3 | 0 | |
| July | 19.9° | 31° | 11° | 114 mm | 4 | 0 | |
| August | 19.7° | 30° | 12° | 107 mm | 0 | 0 | |
| September | 16.1° | 29° | 5° | 35 mm | 2 | 0 | |
| October | 11.4° | 23° | 1° | 41 mm | 7 | 0 | |
| November | 6.7° | 18° | -1° | 47 mm | 11 | 0 | |
| December | 3.5° | 13° | -8° | 48 mm | 11 | 0 |
Lake Tarn
The lake froze at Tarnmund on 24 January 2025, as the towns reported and bore the weight of a man by the end of the month; the ferry to the eastern shore was replaced by a marked path. The thaw is recorded on 22 February 2025.
The Ostra
The river rose to 2.9 metres above its mark at Vellmar bridge at the highest. 54 days of fog were recorded on the lower river, the ferries stopping when the far bank could not be seen.
The Observatory's note
The Tarnmund Observatory certifies the foregoing as the record of 2025, compiled from the Vellmar station, the lakeside station at Tarnmund and the garrison readings at Marschau. Readings on the Osmoor beyond the Reed Line are not taken. The Observatory notes that the front-line report received each evening from the War Ministry makes no mention of the weather at the front, and that none is expected.
Warmest month, 19.9°; coldest, -1.9°. Means are of the month; the warmest day and coldest night are the extremes recorded.
Weather in the public record
- 8 January 2025, Hagenkirchen. The Ostra rises 70 centimetres above its mark at Hagenkirchen. Cellars in Vine Row are flooded. Report.
- 11 January 2025, Norrwick. A storm strips roofs in Norrwick and fells the old lime in New Gate Quay. Report.
- 24 January 2025, Tarnmund. The coldest night in 20 years is recorded at Tarnmund. Lake Tarn freezes to the middle. Report.
- 29 January 2025, Reedtal. The coldest night in 80 years is recorded at Reedtal. Lake Tarn freezes to the middle. Report.
- 8 February 2025, Grauholt. The Ostra rises 50 centimetres above its mark at Grauholt. Cellars in Cooper Lane are flooded. Report.
- 13 February 2025, Ostrabruck. The Ostra rises 40 centimetres above its mark at Ostrabruck. Cellars in Bridge Quay are flooded. Report.
- 20 February 2025, Berging. The Ostra rises 30 centimetres above its mark at Berging. Cellars in Market Walk are flooded. Report.
- 24 February 2025, Weinau. A storm strips roofs in Weinau and fells the old lime in Forge Quay. Report.
- 22 March 2025, Sandfeld. The coldest night in 60 years is recorded at Sandfeld. Lake Tarn freezes to the middle. Report.
- 7 May 2025, Reedtal. A storm strips roofs in Reedtal and fells the old lime in Ostra Street. Report.
- 15 May 2025, Grautal. The coldest night in 70 years is recorded at Grautal. Lake Tarn freezes to the middle. Report.
- 11 June 2025, Eisenheim. The Ostra rises 20 centimetres above its mark at Eisenheim. Cellars in Ostra Square are flooded. Report.
- 25 June 2025, Norrwick. A storm strips roofs in Norrwick and fells the old lime in Orchard Street. Report.
- 8 July 2025, Salzhafen. The coldest night in 30 years is recorded at Salzhafen. Lake Tarn freezes to the middle. Report.
- 15 July 2025, Norrhafen. A storm strips roofs in Norrhafen and fells the old lime in Church Way. Report.
- 5 August 2025, Sudfurt. The Ostra rises 60 centimetres above its mark at Sudfurt. Cellars in Printer Quay are flooded. Report.
- 17 August 2025, Kessel. The coldest night in 20 years is recorded at Kessel. Lake Tarn freezes to the middle. Report.
- 28 August 2025, Eisenheim. The coldest night in 80 years is recorded at Eisenheim. Lake Tarn freezes to the middle. Report.
- 5 September 2025, Hollhausen. The Ostra rises 30 centimetres above its mark at Hollhausen. Cellars in Ferry Square are flooded. Report.
- 18 September 2025, Wasserdorf. The Ostra rises 30 centimetres above its mark at Wasserdorf. Cellars in High Street are flooded. Report.
- 1 November 2025, Tarnmoor. The Ostra rises 20 centimetres above its mark at Tarnmoor. Cellars in Long Way are flooded. Report.
- 1 November 2025, Oberholt. The Ostra rises 60 centimetres above its mark at Oberholt. Cellars in Garrison Square are flooded. Report.
- 19 November 2025, Sandfeld. A storm strips roofs in Sandfeld and fells the old lime in Printer Row. Report.
- 4 December 2025, Brennholt. The coldest night in 50 years is recorded at Brennholt. Lake Tarn freezes to the middle. Report.
- 12 December 2025, Oberbach. A storm strips roofs in Oberbach and fells the old lime in Harbour Row. Report.