Burned area
satellite only7,279ha
Perimeter published by NBAC (NRCan).
- Source
- NBAC (NRCan)
- Date
- 21 May 2018 – 29 May 2018
+− cross-check
No official record is matched to this page to compare it with.
CA · Canada · –
Opportunity No. 17 fire, 21 May 2018 Opportunity No. 17
Out · last detection 29 May 2018, 20:50 UTC
The fire started on 21 May 2018 in Opportunity No. 17, Canada, and satellites saw it burning for 9 days. Canada’s CWFIS (Natural Resources Canada) mapped an official burnt perimeter of 7,279 hectares from satellite imagery, spread across a single census subdivision.
It is the 68th largest in Alberta since 2016 (of 176 with a page). Number 50 in Canada in 2018, of 212.
Use this data
Compare with…
Use this data
Fire page data · version 2026-10-24matches the official recordwith caveatssatellite onlymodel
When copying, the sentence is
Tick the figures you want: they make up the lede and the CSV.
Duration by satellite
satellite only9days
21 May 2018 to 29 May 2018: first and last day with fire on the page.
- Source
- NBAC (NRCan) · NASA FIRMS · VIIRS
- Date
- last detection: 29 May 2018, 20:50 UTC
+− cross-check
Satellites pass a few times a day and cloud or smoke can hide the fire: a lack of detections is not an official extinction. Each country’s emergency service declares a fire contained or out.
Start
satellite only21 May 2018
First day with fire seen by the satellites or the perimeter.
- Source
- NBAC (NRCan) · NASA FIRMS · VIIRS
- Date
- 21 May 2018
+− cross-check
No official record is matched to this page, so the alert time and the cause are not known here.
Hotspots
satellite only581
VIIRS detections at 375 m. Most intense hotspot: 408 MW.
- Source
- NASA FIRMS · VIIRS (Suomi NPP)
- Date
- 21 May 2018 – 29 May 2018
+− cross-check
There is no official record to compare with. Each hotspot is a pixel detected in one satellite pass, not a separate fire.
The worst day
satellite only9,145MW
Total radiative power on 23 May 2018; hotspots that day: 225.
- Source
- NASA FIRMS · VIIRS (FRP)
- Date
- 23 May 2018
+− cross-check
Fire radiative power (FRP) measures the energy the fire gives off when the satellite passes. Added up by day, it compares intensity, not area.
Danger at the start
model25.6FWI · high
Fire Weather Index (Canadian system) computed by WorldFires for the day the fire started. Consecutive days without rain before: 18.
- Source
- WorldFires calculation (Canadian FWI system)
- Date
- 21 May 2018, local noon
- Model
- ERA5 0,25° (ECMWF · Copernicus C3S) · Open-Meteo.com
+− cross-check
This is an index computed from weather model data, not a measurement of the fire nor an official warning. Danger warnings are issued by each country’s authority. Emergency number and official warnings
Weather during the fire
model28.9°C · 20% RH
High of 28.9 °C and minimum humidity of 20% on 23 May 2018; gusts of 51 km/h on 26 May 2018.
- Source
- weather model at the fire’s grid cell
- Date
- 21 May 2018 – 29 May 2018
- Model
- ERA5 0,25° (ECMWF · Copernicus C3S) · Open-Meteo.com
+− cross-check
These are model values for a cell of about 25 km, not from a weather station: they may differ from what was measured on the ground.
This page’s change log has been kept since 24 October 2026: every night what it publishes is compared and the difference is logged. Anything earlier is reconstructed from each source’s date and marked as reconstructed.
Show
-
· reconstructed weatherWeather and FWI computed from the ERA5 reanalysis
-
· reconstructed GHSLPopulation and built-up area computed
What was saved on 24 October 2026
Every night a snapshot of what the page shows is saved. If anything changes, it appears in the list as a log entry.
- Area
- 7,279 ha
- Dates
- 21 May 2018 – 29 May 2018
- Name
- Opportunity No. 17
- Official record
- —
Versioned permanent link
https://worldfires.org/en/fire/opportunity-no-17-2018-05?v=2026-10-24A version keeps the area, dates, name and official record; the area as it was logged (changes under 2% are not logged). The map, hotspots and weather always show today’s data.
Citation
A lede of about 60 words figures only, no adjectives
CSV for this fire opportunity-no-17-2018-05.csv · daily, no individual hotspots
| fecha | focos_viirs | frp_mw | tmax_c | tmin_c | hr_min_pct | viento_max_kmh | racha_max_kmh | precip_mm | fwi | clase_fwi | dentro_del_incendio |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 2018-05-21 | 0 | 0 | 24.6 | 7.5 | 31 | 11.2 | 31.3 | 0 | 25.6 | alto | 1 |
| 2018-05-22 | 14 | 667 | 27.2 | 8.6 | 19 | 11.2 | 27 | 0 | 28.8 | alto | 1 |
| 2018-05-23 | 225 | 9,145 | 28.9 | 9.9 | 20 | 12.4 | 32.8 | 0 | 37 | alto | 1 |
| 2018-05-24 | 250 | 4,498 | 24.7 | 9.2 | 34 | 12.2 | 33.1 | 1 | 33.5 | alto | 1 |
| 2018-05-25 | 67 | 2,235 | 25.2 | 12.3 | 28 | 11.6 | 41.8 | 0.2 | 20.7 | moderado | 1 |
| 2018-05-26 | 0 | 0 | 18.1 | 9.4 | 27 | 20.2 | 50.8 | 3.9 | 7.2 | bajo | 1 |
| 2018-05-27 | 0 | 0 | 20.6 | 7.1 | 29 | 20.2 | 49 | 0 | 17.6 | moderado | 1 |
| 2018-05-28 | 0 | 0 | 22.8 | 9.1 | 26 | 16.6 | 45.4 | 1.3 | 17.4 | moderado | 1 |
| 2018-05-29 | 25 | 571 | 17.2 | 7.6 | 22 | 16.2 | 41.4 | 0 | 23 | alto | 1 |
| 2018-05-30 | 0 | 0 | 12.6 | 5.4 | 50 | 10.5 | 28.8 | 3.9 | 17.7 | moderado | 0 |
It is generated in your browser from this page’s data: one file per fire, aggregated by day and without individual hotspots.
Live widget for your story
It updates itself while the fire is still active and links to this page. Free, with the attribution shown at the bottom.
Sources for this page: NBAC (NRCan), NASA FIRMS (VIIRS), ERA5 (ECMWF/Copernicus C3S) · Open-Meteo.com (CC BY 4.0), GHSL (JRC). Open-Meteo.com · How we build fire pages: methodology
- Burnt area
- 7,279ha
- official perimeter (CWFIS)
- Duration
- 9days
- 21 May 2018 – 29 May 2018
- Census subdivisions hit
- 1
- municipalities
- Started on
- 21 May
- 2018
- Heat detections
- 581
- in a single hotspot: 408 MW
- Danger at start
- 26
- High · FWI index
- Average daily power
- 3.4GW
- detected power per day, on average
Where it burned
HOTSPOTS BY DAY
21 May29 May
29 May 2018
How it evolved, day by day
22 May
23 May
24 May
25 May
29 May
Fire radiative power detected each day, in megawatts, and number of hotspots. The magenta bar marks the peak day.
The weather it burned in
29°high
51km/h · peak gust
19%lowest humidity
It had gone 18 days without rain (1 mm or more) when it started. Rain came after the fire: 3.9 mm on 30 May.
This area had burned before
No earlier perimeters overlap this fire since 2016, when the satellite record begins.
How big is it?
London boundary: geoBoundaries · Office for National Statistics (Open Government Licence v3.0).
Paris boundary: geoBoundaries · Institut national de l'information géographique et forestière (IGN-F) (Etalab Open License 2.0).
Madrid boundary: geoBoundaries · Open Data ESRI, IGN Central Registry of Cartography Area (CC BY 4.0).
Berlin boundary: geoBoundaries · Federal Agency for Cartography and Geodesy (dl-de/by-2-0).
This compares size, not location: both shapes are at the same scale, north up, centred on each other.
What happened to each census subdivision
-
Opportunity No. 17 where it started7,144 ha reached on 22 May0.2 %
Burnt area inside each census subdivision, from crossing the official perimeter with administrative boundaries. The distance runs from the point marking the centre of each area to the nearest fire: staying a kilometre away does not mean it reached the houses.
People and buildings inside the perimeter
GHSL 2020Built-up area< 0.1 ha
Residents< 20
Inside the perimeter there was no noticeable built-up land and almost nobody lived there (GHSL 2020, satellite-based estimate).
This is an estimate on 100 m cells, made from satellite imagery and census data: it does not mean that homes burned or that anyone was harmed. The perimeter also contains land that never burned.
Source: Global Human Settlement Layer (GHS-BUILT-S and GHS-POP R2023A), European Commission Joint Research Centre (JRC), © European Union, CC BY 4.0. Sum inside the perimeter computed by WorldFires. human-settlement.emergency.copernicus.eu
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) |
|---|---|---|---|---|---|
| 21 May | 24.6 °C | 31 % | 31 km/h | 0.0 mm | High 26 |
| 22 May | 27.2 °C | 19 % | 27 km/h | 0.0 mm | High 29 |
| 23 May | 28.9 °C | 20 % | 33 km/h | 0.0 mm | High 37 |
| 24 May | 24.7 °C | 34 % | 33 km/h | 1.0 mm | High 34 |
| 25 May | 25.2 °C | 28 % | 42 km/h | 0.2 mm | Moderate 21 |
| 26 May | 18.1 °C | 27 % | 51 km/h | 3.9 mm | Low 7 |
| 27 May | 20.6 °C | 29 % | 49 km/h | 0.0 mm | Moderate 18 |
| 28 May | 22.8 °C | 26 % | 45 km/h | 1.3 mm | Moderate 17 |
| 29 May | 17.2 °C | 22 % | 41 km/h | 0.0 mm | High 23 |
| 30 May after | 12.6 °C | 50 % | 29 km/h | 3.9 mm | Moderate 18 |
Its twins: fires that started in the same weather
It started with an FWI of 25.6, a minimum humidity of 31% and 18 days without rain. Fires in the area that started in weather like this since 2016: 20.
FWI at the start
25.6
Minimum humidity
31 %
Days without rain
18
this fire
chosen twins
rest of the area
Almost identicalSimilar
Outlines of the closest twins
This fire · Opportunity No. 17 fire, 21 May 2018
7,279 ha
9 days
FWI 25.6
Min. humidity 31 %
Lesser Slave River No.124 fire, May 2023
4,972 ha
6 days
FWI 25.6
Min. humidity 32 %
74 km away, in 2023
First rain (1 mm or more) after it ended: 15.0 mm on 22 May.
Division No. 18, Unorganized fire, July 2021
2,320 ha
38 days
FWI 29.1
Min. humidity 30 %
230 km away, in 2021
First rain (1 mm or more) after it ended: none in the following ten days.
Wood Buffalo fire, July 2024
1,370 ha
7 days
FWI 26.1
Min. humidity 26 %
143 km away, in 2024
First rain (1 mm or more) after it ended: 12.0 mm on 24 Jul.
Wood Buffalo fire, July 2024
4,460 ha
29 days
FWI 20.4
Min. humidity 32 %
185 km away, in 2024
First rain (1 mm or more) after it ended: 4.5 mm on 18 Aug.
Improvement District No. 349 fire, July 2024
1,140 ha
34 days
FWI 19.8
Min. humidity 30 %
156 km away, in 2024
First rain (1 mm or more) after it ended: 4.1 mm on 20 Aug.
What happened to them
- 30 days
- median duration
- 3,604 ha
- median area
- 25 %
- went past 10,000 ha
- 4.2 mm
- rain at the end (median; 19 of 20 had it)
It was 2.0 times larger than the median of its twins and lasted 9 days, against 30 days.
Only 5 of its 20 twins burned more. The weather on the first day does not explain everything: the wind in the following days, the fuel and the firefighting also count. In 1 of 20, not even 1 mm fell in the ten days after the end: they went out without rain. In the rest, the first rainy day brought a median of 4.2 mm.
This is a bank of analogues: it shows what usually happens, not what will happen. With fewer than 15 twins we give no figures. How we calculate it
How it ended
3.9 mmfirst rain
30 Maythe day after it ended
51km/h · max. gust
It was considered over on 29 May, and on 30 May 3.9 mm fell. We do not know whether the rain or the firefighters put it out. Twins with rain when they ended: 19 of 20, with a median of 4.2 mm.
Weather on this page: Open-Meteo.com (CC BY 4.0) · Copernicus Climate Change Service (ERA5)
How a twin is chosen
- Same area: fires that have already ended, less than 250 km from this one, since 2016.
- Same start: we compare the FWI on the first day, the minimum humidity that day and the run of days without rain before it. The slider sets how much they may differ.
- Only pages with final weather data (ERA5 reanalysis) calculated in the same way as this fire’s; agricultural and grass burns and pages with data under review are left out.
- Fires burning at the same time as this one (a week before or after) are left out: they share the same spell of weather and do not count as a precedent.
- They are sorted by similarity, and the outlines of the first five are drawn.
Before and after, from space
Drag the line to compare the same ground before the fire and after it.
↔
Before · 14 May 2018
After · 5 Jun 2018
Sentinel-2 did not pass over on that day. Try another date, or use false colour, which is daily.
If the day is cloudy, change the date: each satellite passes once a day. In false colour the burnt ground looks brown or red.
Detections table · 581Every satellite heat detection, one by one, with time, satellite, power and coordinates.
⬇ Download CSV
Times in UTC. Each detection is a 375 m pixel: a large fire yields hundreds per pass.
| Date and time | Satellite | FRP (MW) | Lat | Lon |
|---|
Other fires nearby
Frequently asked questions
- How long did the Opportunity No. 17 fire last?
- It burned between 21 May 2018 and 29 May 2018: 9 days, according to the dates recorded by Canada’s CWFIS and the heat detections seen by satellite.
- How much area did it burn?
- The official perimeter mapped by Canada’s CWFIS (Natural Resources Canada) is 7,279 hectares (72.8 km²). Other tallies, such as those of provincial agencies, may give slightly different figures.
- Which census subdivisions burned?
- The fire only entered Opportunity No. 17 (7,144 ha, 0.2 %).
- What was the weather like?
- During the fire the temperature reached 28.9 °C, humidity dropped to 19 % and gusts hit 51 km/h. The fire danger index (FWI) reached 37, class High.
- Where does this data come from?
- From the official burnt perimeter of Canada’s CWFIS (NBAC, Natural Resources Canada) or, for the current season and until NBAC publishes it, the one rebuilt by GWIS (Copernicus); from NASA FIRMS VIIRS hotspots; and from the administrative boundaries of Canada. It is not an official report.
- How did the fires that started in similar weather in this area end?
- Fires less than 250 km away that started since 2016 with a similar FWI, humidity and dry spell: 20. Their median duration was 30 days and their median area 3,604 ha; 25 % went past 10,000 ha. Only 5 of its 20 twins burned more. The weather on the first day does not explain everything: the wind in the following days, the fuel and the firefighting also count. In 1 of 20, not even 1 mm fell in the ten days after the end: they went out without rain. In the rest, the first rainy day brought a median of 4.2 mm.
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 · Emergency number and official warnings
- CIFFC · Canadian Interagency Forest Fire Centre ↗
- CWFIS · Canadian Wildland Fire Information System ↗
Satellite cross-check
History of this page Changes in area, dates, name, official record or merged pages, compared every night since 24 October 2026.
No changes since 24 October 2026.
RSS Changes to this page With cross-checks and a citable version
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
How we know this
- Perimeter: NBAC (Natural Resources Canada), official.
- Dates from the perimeter: the VIIRS detections inside it did not change them. 581 Suomi-NPP VIIRS detections on those dates.
- We have not matched this page with any official record.
- Weather: Copernicus ERA5 reanalysis at the fire location, in cells of about 25 km.
- Built-up area and population come from the JRC Global Human Settlement Layer (epoch 2020, 100 m cells), summed inside the perimeter: an estimate of what was there, not a damage count.
Where this data comes from
The perimeter is official: it comes from the National Burned Area Composite (NBAC) of the Canadian Wildland Fire Information System (CWFIS), Natural Resources Canada, which maps it on satellite imagery and publishes it under the Open Government Licence – Canada. Until NBAC publishes the current season, this year’s fires carry the perimeter rebuilt from heat detections by GWIS (Copernicus, CC BY 4.0), which is approximate. Heat detections come from the VIIRS sensors aboard Suomi-NPP and NOAA-20, distributed by NASA FIRMS at 375 m resolution. Census subdivision boundaries come from geoBoundaries ADM3 (Open Data Commons Open Database License 1.0). The area per census subdivision is computed by WorldFires by crossing the perimeter with those boundaries, so it may differ slightly from official figures.