The HANZE dataset covers riverine, pluvial, coastal and compound floods that have occurred in 42 European countries between 1870 and 2025. The data was collected by extensive data-collection from more than 1000 sources ranging from news reports through government databases to scientific papers. The dataset includes 2724 events characterized by at least one impact statistic: area inundated, fatalities, persons affected or economic loss. Economic losses are presented both in the original currencies and price levels as well as inflation and exchange-rate adjusted to 2025 value of the euro. The spatial footprint of affected areas is consistently recorded using more than 1400 subnational units corresponding, with minor exceptions, to the European Union’s Nomenclature of Territorial Units for Statistics (NUTS), level 3, or International Territorial Levels (ITL), level 3 for the UK. Daily start and end dates, information on causes of the event, notes on data quality issues or associated non-flood impacts, and full bibliography of each record supplement the dataset. Apart from the possibility to download the data, the database can be viewed, filtered and visualized online: https://naturalhazards.eu. The dataset is designed to be complimentary to HANZE-Exposure, a high-resolution model of historical exposure changes (such as population and asset value), and be easily usable in statistical and spatial analyses. This is a second preliminary update of HANZE v2.1, adding 181 floods for years 2021-2025. It makes only minor revisions to previous data (adds 25 pre-2021 events, revises 49 records and removes 3 events that were newly reassessed as non-flood events). A more extensive revision of the data is planned for 2026. The dataset contains the following files (CSV comma-delimited, UTF8, and ESRI shapefiles in zipped folders) HANZE flood events database HANZE_events_v3_0_1b.csv - Flood event data HANZE_references_v3_0_1b.csv - List of all references HANZE_events_regions_v3_0_1_b_2024.zip - Flood event data as GIS file (regions v2024) Supplementary data S1_countries_codes_and_names.csv - Country codes/names S2_regions_codes_and_names_v2024.csv - Region codes/names, v2024 S3_list_of_all_currencies_by_country.csv - Data on all currencies used in the study area since 1870 S4_currency_conversion_rates.csv - Conversion rates applied to compute losses in 2025 euros S5_GDP_deflators_by_country.csv - Gross domestic product deflator by country, 1870-2025 S6_floods_removed_from_HANZE.csv - Flood events in HANZE v1 and v2, which were excluded from v3 Regions_v2024_simplified.zip - Map of subnational regions used in the database, v2024

This update of the HANZE database was supported by European Commission Joint Research Centre through contracts EC JRC/IPR/2025/VLVP/126 9 and no. 300148976. HANZE v2 was supported by the German Research Foundation (DFG) through project "Decomposition of flood losses by environmental and economic drivers" (FloodDrivers), project no. 449175973