Reference data analysis
What the year comparison shows for Lake Constance
Typical low point
395.06 m a.s.l.
February 17
Typical high point
396.24 m a.s.l.
June 19
Typical range
118 cm
Difference between daily medians
In the 1991-2020 reference period, Lake Constance's seasonal median is lowest on February 17 at 395.06 m a.s.l. and highest on June 19 at 396.24 m a.s.l.. The difference between these typical points is 118 cm. This describes the average seasonal cycle, not the largest individual fluctuation.
The 2026 curve currently contains 265 calendar days. On September 22 it shows 394.78 m a.s.l., which is 97 cm below that calendar day's median of 395.75 m a.s.l.. Compared with the same calendar day in 2025, the value is 85 cm lower.
Within the 1991-2020 reference period, the envelope reaches its highest value of 397.89 m a.s.l. on June 11 and its lowest value of 394.50 m a.s.l. on February 13. These are extremes of the displayed reference period, not all-time records.
The analysis uses the water-level series from Romanshorn. Matching calendar days are compared, and the median is the middle value of the reference years. This classification does not replace flood warnings or local safety information.