Sea of fog calendar

Name: Sea of fog calendar: days with a sea of fog in the SwissMetNet network
Creator: MeteoSwiss
License: https://creativecommons.org/licenses/by/4.0/

Most often in December: a sea of fog on 52 of 186 measured days.

Counted, not estimated: the days on which MeteoSwiss' SwissMetNet stations measured a sea of fog, month by month – and how often the summits stood above the fog lid.

Measured from 01.01.2020 to 08.11.2026 · Source: MeteoSwiss, SwissMetNet stations

Days with a sea of fog

Days with a sea of fog per month · 2020–2026

A sea of fog on 186 of 2’504 measured days

Each bar counts the days of a month on which the stations measured a sea of fog – all measured years together. The month with the largest share is highlighted.

Latest measured

Summit by summit: days above the sea of fog

How often a summit stood at least 100 m above the day's highest fog lid on a day with a sea of fog – per month, all measured years together.

Days above the sea of fog per summit and month
Summit	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sept	Oct	Nov	Dec
Titlis3’062 m	37	15	10	3	1	–	–	2	–	24	42	52
Säntis2’502 m	37	15	10	3	1	–	–	2	–	24	42	52
Chäserrugg2’260 m	32	13	6	2	1	–	–	2	–	20	39	47
Stockhorn2’190 m	31	13	6	2	1	–	–	2	–	20	38	47
Pilatus2’119 m	31	13	6	2	1	–	–	2	–	20	38	47
Rochers de Naye2’042 m	23	11	6	1	–	–	–	2	–	20	37	39
Niederhorn1’964 m	22	11	6	–	–	–	–	2	–	20	37	38
Stanserhorn1’898 m	20	9	3	–	–	–	–	1	–	17	33	34
Rigi1’797 m	20	9	3	–	–	–	–	1	–	17	33	33
Kronberg1’663 m	18	5	2	–	–	–	–	–	–	14	32	30
Les Pléiades1’362 m	12	3	–	–	–	–	–	–	–	8	12	23
Uetliberg872 m	1	–	–	–	–	–	–	–	–	3	1	2

Every day with a sea of fog

Each day with its fog report: the fog lid, the sun at every station and the summits above it.

January: 37

February: 15

March: 10

April: 3

May: 1

Tue, 12.05.2020Fog lid 1’500–2’000 m · 3 of 36 Plateau stations without sun

August: 2

October: 24

November: 42

December: 52

How it is counted

Every MeteoSwiss station measures how many minutes of each hour the sun shines. When the low stations see hardly any sun and higher ones plenty, a sea of fog lies in between; its lid lies between the highest station in fog and the lowest in the sun.

A day with a sea of fog has one in at least half of its hours with the sun high, measured north of the main Alpine ridge. A summit counts when it stands 100 m above the day's highest lid. Nothing is modelled: every figure counts measured days, and every new day is added.

Fog level and sea of fog today

Source: MeteoSwiss