Burning Unseen: How Long Do Satellite-Detected Wildfires in Europe and the Mediterranean Take to Reach the Public, and How Much Do They Grow in the Meantime?

This preprint is the ISYC edition of an original research paper written by young researchers of the International Scientific Youth Community (ISYC). Polar-orbiting satellites detect active wildfires within hours, but it was not known how long this information takes to reach the public, or how much fires grow in the meantime. We built an automated database that collected NASA FIRMS active-fire detections (VIIRS and MODIS) for Europe and the Mediterranean from 10 August to 10 October 2026. After clustering 273,273 detections and removing industrial heat sources, crop burns and artefacts, 345 wildfires in 23 countries remained. For each fire we recorded when it first appeared in the public satellite feed, GDACS, Copernicus Emergency Management Service activations, verified news articles and Wikipedia. The satellite feed made a fire public after a median of 2.2 hours, Copernicus EMS was activated after 18.8 hours, and the first news article appeared after 29.7 hours; 77 % of fires never reached the news. The median fire covered 52 ha when it first appeared in the satellite feed and 557 ha by the time of its first news article. From 183 spreading fires we derived a simple growth equation that estimates the area burned between satellite overpasses, with a median error of 8.4 % on 1,291 growth steps, and tested it on ten well-known Californian fires with official reports.