Yonne

Recorded Natural Hazards (Géorisques)

It has 423 municipalities and 332,267 inhabitants. Under the seismic zoning in force since 2011, its highest seismicity is very low (zone 1 of 5). A natural disaster has been declared 2,040 times since 1982 (one declaration per municipality and decree), mostly for floods (1,070) and drought (537). The most recent was signed on 8 July 2025. 20 municipalities have a high radon potential (category 3), home to 4% of inhabitants. 165 municipalities are covered by an approved natural hazard prevention plan.

Seismicity Zones

Number of municipalities in each zone of the regulatory seismic zoning (from 1, very low, to 5, high).

Natural Disasters Declared Since 1982

Declarations per five-year period.

Most Widespread Events

• 1999Ground Movements · 25 December 1999421 municipalities
• 1999Floods and Mudflows · 25 December 1999421 municipalities
• 2018Drought (Clay Shrinkage) · 1 July 2018121 municipalities
• 2019Drought (Clay Shrinkage) · 1 July 201995 municipalities
• 1998Floods and Mudflows · 25 April 199839 municipalities
• 2022Drought (Clay Shrinkage) · 1 April 202236 municipalities

Most Frequently Affected Municipalities

• 21Auxerre
• 17Saint-Florentin
• 17Sens
• 17Tonnerre
• 15Avallon
• 15Monéteau
• 14Joigny
• 14Saint-Georges-sur-Baulche

Hazards Listed by Municipality

Number of municipalities exposed to each natural hazard according to the departmental major risks file.

Hazards at a specific address on Géorisques