Castelnau-de-Guers Fire 2025 — Burn Severity Map & Satellite Analysis
Tue Jul 08 2025 00:00:00 GMT+0000 (Coordinated Universal Time)
About this fire
On 8 July 2025, a violent wildfire broke out in Castelnau-de-Guers, a wine-growing commune in the Hérault department of Occitanie. The fire spread rapidly across 700 hectares — 400 of them severely burned — advancing 3.5 kilometers through garrigue and vineyard edges in the Languedoc wine country. The blaze was one of nine simultaneous fire starts in the Hérault that day, eight of which were stopped at an early stage by rapid-response firefighting teams.
The fire directly threatened the Languedoc AOP vineyards that define the region’s economy and identity. While firefighters managed to save 220 caravans and eight agricultural estates (mas) in the fire’s path, initial field assessments indicated significant damage to vineyards exposed to the flames. The A9 motorway was briefly threatened before traffic was restored as the situation stabilized.
At peak deployment, 750 firefighters were engaged, with 430 still on scene at 21:30. Six Canadair water-bombers provided continuous aerial support until nightfall. No homes were destroyed and no casualties were reported — a testament to the speed and coordination of the response. The Hérault prefect publicly commended the firefighters, both professional and volunteer, for their work under extreme conditions.
Timeline & severity
| Date | Event |
|---|---|
| 8 Jul 2025 (afternoon) | Fire ignites at Castelnau-de-Guers; 9 simultaneous starts in Hérault |
| 8 Jul 2025 (evening) | 700 ha burned (400 severely); A9 motorway threatened then reopened |
| 8 Jul 2025 (night) | 430 firefighters on scene; 6 Canadairs active until nightfall |
| 9 Jul 2025 | Fire stabilized; vineyard damage assessment begins |
| Post-fire | 700 ha burned; 220 caravans saved; 8 estates protected; vineyard damage reported |
The fire’s spread through vineyard edges is particularly significant for the Languedoc wine industry. Even where vines were not directly burned, heat exposure can damage vine physiology and smoke can taint ripening grapes — financial losses that extend well beyond the visible fire perimeter.
Satellite analysis
Sentinel-2 satellite imagery provides the clearest picture of fire impact and recovery among the four July 2025 fires analyzed.
Burn severity (dNBR)
| Metric | Value | Image date |
|---|---|---|
| Pre-fire NBR | 0.185 | 10 Jun 2025 |
| Post-fire NBR | 0.125 | 3 Sep 2025 |
| dNBR | 0.060 | — |
| USGS severity class | Unburned (area average) | — |
The dNBR of 0.060 is the highest among the four July–August 2025 French fires analyzed, approaching the USGS “low severity” threshold (0.1). The NBR dropped 32% from 0.185 to 0.125 — a significant vegetation loss. While the area-average classification remains “unburned” (due to the garrigue’s naturally low biomass and unburned patches within the bounding box), the NBR decline is substantial enough to confirm real fire damage at the vegetation level.
Vegetation timeline
| Period | NDVI | NBR | NDMI | Context |
|---|---|---|---|---|
| Jan 2024 | 0.300 | 0.170 | 0.069 | Winter baseline |
| Jul 2024 | 0.298 | 0.146 | 0.019 | Summer drought — NDMI near zero |
| Dec 2024 | 0.295 | 0.169 | 0.078 | Pre-fire winter |
| Jun 2025 | — | 0.185 | — | Pre-fire image — healthy vineyard/garrigue |
| 8 Jul 2025 | — | — | — | Fire ignites |
| Sep 2025 | — | 0.125 | — | Post-fire image — NBR dropped 32% |
| Jul 2026 | 0.304 | 0.187 | 0.050 | 1 year post-fire — NBR fully recovered |
Key findings
The Castelnau-de-Guers data shows the clearest fire-and-recovery trajectory of all four fires. Pre-fire NBR (0.185) dropped to 0.125 after the fire — a 32% decline indicating significant vegetation damage. One year later, NBR has recovered to 0.187 — slightly above the pre-fire value, indicating full vegetation regrowth. This rapid recovery is consistent with garrigue scrubland, which is adapted to fire and resprouts vigorously.
However, current NDMI (0.050) is in the “transitional, increasing fire risk” zone, and the NDVI (0.304) remains moderate rather than high — the regrowth consists of pioneer garrigue species, not the vineyard vegetation that was damaged. For wine growers, this means the natural vegetation has recovered, but vineyard parcels that burned may still need replanting. Satellite monitoring of NDVI at the parcel level over the coming seasons will distinguish recovering vines from those requiring replacement.
Read our full guide: What is NBR? →
Recovery outlook
The Castelnau-de-Guers fire burned through a mosaic of garrigue and vineyards. Garrigue vegetation is fire-adapted and expected to regrow within 1–2 years, but the loss of ground cover creates erosion risk on the sloped terrain before autumn rains. For vineyard owners, the recovery timeline depends on burn severity: lightly scorched vines may resume normal growth the following season, while severely burned vines require replanting — a 3–5 year setback before the first harvest. Satellite monitoring of NDVI regrowth over the coming months will help growers identify which vines are recovering and which need replacement, and will track garrigue regeneration to inform future fuel management in the Languedoc wine corridor.
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