Reference data analysis
What the year comparison shows for Lake Geneva
Typical low point
371.66 m a.s.l.
April 21
Typical high point
372.24 m a.s.l.
July 7
Typical range
58 cm
Difference between daily medians
In the 1991-2020 reference period, Lake Geneva's seasonal median is lowest on April 21 at 371.66 m a.s.l. and highest on July 7 at 372.24 m a.s.l.. The difference between these typical points is 58 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 372.23 m a.s.l., which is 4 cm above that calendar day's median of 372.18 m a.s.l.. Compared with the same calendar day in 2025, the value is 7 cm higher.
Within the 1991-2020 reference period, the envelope reaches its highest value of 372.51 m a.s.l. on July 29 and its lowest value of 371.32 m a.s.l. on April 23. These are extremes of the displayed reference period, not all-time records.
The analysis uses the water-level series from Genève-Sécheron. 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.