Reference data analysis
What the year comparison shows for Lake Sempach
Typical low point
503.64 m a.s.l.
October 10
Typical high point
503.78 m a.s.l.
July 12
Typical range
14 cm
Difference between daily medians
In the 1991-2020 reference period, Lake Sempach's seasonal median is lowest on October 10 at 503.64 m a.s.l. and highest on July 12 at 503.78 m a.s.l.. The difference between these typical points is 14 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 503.36 m a.s.l., which is 32 cm below that calendar day's median of 503.68 m a.s.l.. Compared with the same calendar day in 2025, the value is 51 cm lower.
Within the 1991-2020 reference period, the envelope reaches its highest value of 504.34 m a.s.l. on August 10 and its lowest value of 503.39 m a.s.l. on September 12. These are extremes of the displayed reference period, not all-time records.
The analysis uses the water-level series from Sempachersee, Sempach. 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.