Alonsa fire, 4 May 2025 Alonsa
The fire started on 4 May 2025 in Alonsa, Canada, and satellites saw it burning for 7 days. Copernicus’s global GWIS system rebuilt a burnt perimeter of 4,530 hectares from heat detections, spread across a single municipality.
It is the 201th largest in Manitoba since 2016 (of 509 with a page). Number 233 in Canada in 2025, of 669.
- Burnt area
- 4,530ha
- GWIS perimeter (Copernicus)
- Duration
- 7days
- 4 May 2025 – 10 May 2025
- Municipalities hit
- 1
- municipalities
- Started on
- 4 May
- 2025
- Heat detections
- 681
- in a single hotspot: 253 MW
- Danger at start
- 1
- Very low · FWI index
- Energy released
- 8.9GW
- sum of detected power
Where it burned
How it evolved, day by day
Fire radiative power detected each day, in megawatts, and number of hotspots. The magenta bar marks the peak day.
The weather it burned in
It had gone 0 days without rain (1 mm or more) when it started. Rain came after the fire: 7.1 mm on 14 May.
This area had burned before
No earlier perimeters overlap this fire since 2016, when the satellite record begins.
What happened to each town
-
Alonsa where it started4,551 ha reached on 1 May1.4 %
Burnt area inside each municipality, from crossing the GWIS perimeter with administrative boundaries. The distance is from the town centre to the nearest fire: staying a kilometre away does not mean it reached the houses.
The weather day by day
ECMWF ERA5 reanalysis at the fire location, the standard reference for past weather, and the Canadian Fire Weather Index (the same system Copernicus uses), computed by WorldFires from that data. Days after the fire run until the first rain.
Open-Meteo.com (CC BY 4.0) · Copernicus Climate Change Service (ERA5)
| Day | High | Min. humidity | Peak gust | Rain | Danger (FWI) |
|---|---|---|---|---|---|
| 1 May | 8.1 °C | 66 % | 39 km/h | 0.1 mm | Very low 1 |
| 2 May | 15.8 °C | 38 % | 33 km/h | 0.0 mm | Very low 4 |
| 3 May | 14.5 °C | 39 % | 44 km/h | 0.0 mm | Low 8 |
| 4 May | 24.5 °C | 26 % | 41 km/h | 0.0 mm | Moderate 14 |
| 5 May | 17.5 °C | 45 % | 43 km/h | 0.5 mm | Moderate 12 |
| 6 May | 10.0 °C | 38 % | 35 km/h | 0.0 mm | Low 10 |
| 7 May | 15.4 °C | 32 % | 36 km/h | 0.0 mm | Low 11 |
| 8 May | 24.8 °C | 34 % | 50 km/h | 0.0 mm | Moderate 17 |
| 9 May | 19.2 °C | 26 % | 53 km/h | 0.0 mm | Moderate 19 |
| 10 May | 21.2 °C | 31 % | 56 km/h | 1.4 mm | Moderate 12 |
| 11 May after | 20.7 °C | 39 % | 34 km/h | 0.9 mm | Moderate 11 |
| 12 May after | 22.1 °C | 50 % | 28 km/h | 0.0 mm | Moderate 13 |
| 13 May after | 22.0 °C | 43 % | 60 km/h | 0.0 mm | Moderate 18 |
| 14 May after | 9.1 °C | 79 % | 48 km/h | 7.1 mm | Very low 0 |
Before and after, from space
Drag the line to compare the same ground before the fire and after it.
If the day is cloudy, change the date: each satellite passes once a day. In false colour the burnt ground looks brown or red.
The smoke
CAMS · CopernicusOn 6 May 2025 the air beside the fire reached 55 µg/m³ of PM2.5. That day averaged 29: 2.0 times the WHO daily guideline (15).
Particles from the Copernicus CAMS model at the centre of the perimeter; these are not measurements in each town. The pale bar is the worst hour, the solid one the daily average.
Open-Meteo.com (CC BY 4.0) · Copernicus Atmosphere Monitoring Service (CAMS)
Detections table · 681Every satellite heat detection, one by one, with time, satellite, power and coordinates.
| Date and time | Satellite | FRP (MW) | Lat | Lon |
|---|
Other fires nearby
Frequently asked questions
- How long did the Alonsa fire last?
- GWIS (Copernicus) dates it between 4 May 2025 and 10 May 2025: 7 days between the first and last heat detection of the perimeter.
- How much area did it burn?
- The perimeter GWIS (Copernicus) rebuilt from heat detections is 4,530 hectares (45.3 km²). It is an estimate: official national figures may differ.
- Which municipalities burned?
- The fire only entered Alonsa (4,551 ha, 1.4 %).
- What was the weather like?
- During the fire the temperature reached 24.8 °C, humidity dropped to 26 % and gusts hit 56 km/h. The fire danger index (FWI) reached 19, class Moderate.
- Where does this data come from?
- From the GWIS (Copernicus) burnt perimeter, NASA FIRMS VIIRS hotspots and the administrative boundaries of Canada (geoBoundaries). It is not an official report.
Where to verify it
A satellite detection is not an official report. Final figures and the fire’s status are published by each country’s emergency service.
Emergency number: 911
- CIFFC · Canadian Interagency Forest Fire Centre ↗
- CWFIS · Canadian Wildland Fire Information System ↗
Satellite cross-check
Does something look wrong on this page?
This page is built from satellite data and official records, and it sometimes gets things wrong: the wrong dates, the wrong town, two fires merged into one, or something that was not a wildfire at all. If you know this fire first-hand (you live nearby, saw it, fought it or reported on it), tell us what really happened and we will check it.
Report an error
Where this data comes from
The perimeter comes from the Copernicus Global Wildfire Information System (GWIS), which rebuilds it from MODIS and VIIRS heat detections and publishes it under CC BY 4.0. It is not measured on imagery as in Europe, so it is an estimate. Heat detections come from the VIIRS sensors aboard Suomi-NPP and NOAA-20, distributed by NASA FIRMS at 375 m resolution. Municipal boundaries come from geoBoundaries ADM3 (Open Data Commons Open Database License 1.0). The area per municipality is computed by WorldFires by crossing the perimeter with those boundaries, so it may differ from each country’s official figure.