Lightning and thunderstorms
Switzerland 2024 review
Read our weather, climate and electrical analysis of thunderstorms in Switzerland in 2024.
2024 at a glance
Joris Royet, Chef de projet Météo, METEORAGE
A particularly electric summer
With more than 50,000 CG cloud-to-ground flashes (lightning strikes) detected, 2024 was one of the years with the highest number of lightning strikes, although not one of the five most active years.
After a stable spring, electrical activity peaked during the meteorological summer (June, July and August).
June 2024 stood out with more than 18,000 cloud-to-ground lightning flashes, making it the fourth most lightning-flashed June since METEORAGE began recording data.
This intense activity can be explained by the presence of cold drops which generated thunderstorm fronts crossing France before reaching Switzerland.
A quiet end to the year
Thunderstorm activity dropped off rapidly after the summer, becoming virtually non-existent in October, November and December.
Joris Royet, Weather Project Manager, METEORAGE.
Our European Lightning Detection Network (ELDN) detected in Switzerland, in 2024
Key facts
The day most struck by lightning
31 July 2024
The month most struck by lightning
June 2024
The town most struck by lightning
Lavizzara
Focus on
by Joris Royet, Weather Project Manager, METEORAGE.
On 29 June 2024, a low-pressure system moving from France towards southern Germany brought warm, humid and unstable air to the Swiss Alps. This, combined with stronger southerly winds at altitude, encouraged the development of severe thunderstorms, which were particularly marked in the south and west of Switzerland.
The CAPE (Convective Available Potential Energy), which was very high over the Jura mountains, contributed to the intensification of these convective systems in the border areas. The first thunderstorm cells formed from midday in a dynamic south-westerly flow, impacting Valais and Ticino in particular. At the end of the day, the heaviest thunderstorms arrived from France along the Franco-Swiss border, with violent phenomena observed in these areas.
The storm systems moved across Germany, Belgium, Luxembourg and the rest of Switzerland, causing intense phenomena such as impressive mudslides in Zermatt. In this region, the Simplon Pass was particularly hard hit, with several roads closed due to torrential debris flows.
The episode was also characterised by a high level of electrical activity: more than 4,600 cloud-to-ground lightning flashes were detected on Saturday 29 June, making it one of the most lightning-stricken days of 2024.
CG lightning strike map for 29 June 2024
On 29 June 2024, 4,636 CG flashes were detected, including :
– 4,475 negative CG flashes,
+ 161 positive CG flashes.
Lightning strikes in Switzerland in 2024
For 2024, the lightning density of cloud-to-ground flashes (lightning strikes) in Switzerland is 1.2104 CG cloud-to-ground flashes per km².
Seasonality of thunderstorms
Seasonal distribution of CG cloud-to-ground lightning flashes
The frequency, geographical distribution and intensity of thunderstorms vary with the seasons , depending on temperature, humidity and atmospheric dynamics.
In spring, thermal contrasts between cold and warm air set in and encourage the first convective thunderstorms, often accompanied by intense rain and sometimes hail or tornadoes, with electrical activity increasing as the season progresses.
In summer, they are more frequent and violent, fuelled by high temperatures and strong contrasts when cold drops pass through, generating thunderstorms that are sometimes supercellular, hence a peak in activity during this season.
Autumn sees a gradual reduction in electrical activity, but lows, or cold drops, can still produce frontal thunderstorms linked to transitions between air masses, or at the back in the case of trailing skies.
In winter, although less frequent, thunderstorms can occur, often behind a disturbance where the cool air near the ground contrasts with very cold air aloft. These thunderstorms appear anarchically within an unstable air mass.
Top 10 cantons most struck by lightning
by number of cloud-to-ground (CG) lightning flashes
by lightning density of cloud-to-ground (CG) lightning flashes per km²/year
| 01. APPENZELL-INNERRHODEN | 3.415 |
| 02. GENÈVE | 2.371 |
| 03. TICINO | 2.357 |
| 04. ZUG | 2.123 |
| 05. APPENZELL-AUSSERRHODEN | 2.121 |
| 06. SCHWYZ | 1.976 |
| 07. OBWALDEN | 1.869 |
| 08. LUZERN | 1.861 |
| 09. NIDWALDEN | 1.773 |
| 10. VAUD | 1.425 |
Top 10 districts most struck by lightning
by number of cloud-to-ground (CG) lightning flashes
by lightning density of cloud-to-ground (CG) lightning flashes per km²/year
| 01. LUGANO | 3.706 |
| 02. APPENZELL-INNERRHODEN | 3.415 |
| 03. MENDRISIO | 3.390 |
| 04. BELLINZONA | 3.196 |
| 05. LOCARNO | 2.578 |
| 06. COSSONAY | 2.569 |
| 07. HINTERLAND | 2.535 |
| 08. KÜSSNACHT | 2.422 |
| 09. TRACHSELWALD | 2.372 |
| 10. GENÈVE | 2.371 |
Top 10 municipalities most struck by lightning
by number of cloud-to-ground (CG) lightning flashes
by lightning density of cloud-to-ground (CG) lightning flashes per km²/year
| 01. CANOBBIO | 9.283 |
| 02. PLAN-LES-OUATES | 7.133 |
| 03. PURA | 6.720 |
| 04. CERTARA | 6.678 |
| 05. ASTANO | 6.602 |
| 06. RIVERA | 6.570 |
| 07. SAGNO | 6.551 |
| 08. CARABBIA | 6.528 |
| 09. ONEX | 6.382 |
| 10. MEZZOVICO-VIRA | 6.278 |
The lightning strikein Switzerland in recent years
Since 2007, the lightning density of cloud-to-ground CG flashes (lightning strikes) in Switzerland has been 0.5288 cloud-to-ground CG flashes/km² per year.
The average number of days with thunderstorms is 149 per year.
Over the last 3 years
Monthly distribution of lightning strikes
Number of cloud-to-ground (CG) lightning flashes detected each month.
Over the last 10 years
Annual distribution of lightning strikes
Number of cloud-to-ground (CG) lightning flashes detected each year.
Annual distribution of thunder days
Number of thunder days detected annually.
Terminology
To help you better understand the information in this report, here are the definitions for some of the most frequently used terms.
Cloud-to-ground (CG) lightning flash
Discharge of current of a certain intensity circulating between the cloud and the ground. Abbreviated to CG (Cloud-to-Ground).
Lightning density
The best current representation of thunderstorm activity is lightning density, which is the number of cloud-to-ground (CG) lightning flashes per km² per year.
Lightning flash
All current discharges and electrical impulses from a lightning event. A lightning flash can occur within the same cloud (IC), between a cloud and the ground (CG) or between two clouds (CC). A lightning flash can be composed of one stroke or many strokes, which are current discharges and electrical impulses.
Thunder day
Each day that lightning was detected in a given area.
About this lightning report
The lightning report is based on data provided by METEORAGE’s lightning detection network (ELDN) in Europe.
The information we provide concerns cloud-to-ground (CG) lightning flashes and lightning density.
To be able to compare these data with the data collected, METEORAGE counts the main current pulse circulating between the cloud and the ground, defined in this report by the term “Cloud-to-ground (CG) lightning flash”.
Our expertise draws on more than ten years of analysis, observation and data collected in Europe, and more broadly worldwide. We have over 37 years’ expertise in France.
The performance of our network has been validated scientifically and delivers the best possible results with:
- > 98% lightning flash detection,
- a median detection accuracy of 100 meters,
- > 90% distinction made between cloud-to-ground (CG) lightning flashes and intra-cloud lightning flashes.
The METEORAGE network consists of more than 100 lightning sensors, calculators and a processing system that manages the databases. Our lightning sensors are based on the Vaisala technology, currently considered one of the best in the world. Our network achieves levels of performance validated by numerous scientific studies and publications.
This 2024 report is based on the most comprehensive source of information in Switzerland. The data, densities, rankings and thunder days in this report are dated from 1 January 2024 to 31 December 2024.
