Phrao fire, 4 April 2023 พร้าว · Phrao
The fire started on 4 April 2023 in Phrao, Thailand, and satellites saw it burning for 4 days. Copernicus’s global GWIS system rebuilt a burnt perimeter of 1,021 hectares from heat detections, spread across a single municipality.
It is the 383th largest in Chiang Mai Province since 2016 (of 399 with a page). Number 355 in Thailand in 2023, of 370.
The power measured by the satellite is low (7.5 MW in the strongest hotspot), more typical of grass or stubble burning, or a slow surface fire, than of a large crown fire.
Compare with…
- Burnt area
- 1,021ha
- GWIS perimeter (Copernicus)
- Duration
- 4days
- 4 Apr 2023 – 7 Apr 2023
- Municipalities hit
- 1
- districts
- Started on
- 4 Apr
- 2023
- Heat detections
- 31
- in a single hotspot: 7 MW
- Danger at start
- 31
- High · FWI index
- Average daily power
- 12MW
- detected power per day, on average
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 11 days without rain (1 mm or more) when it started.
This area had burned before
21% of the perimeter overlaps earlier fires recorded since 2016: 7 ha in 2016, 204 ha in 2020.
How big is it?
London boundary: geoBoundaries · Office for National Statistics (Open Government Licence v3.0).
Bangkok boundary: geoBoundaries · OpenStreetMap, Wambacher · © OpenStreetMap contributors (ODbL 1.0).
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).
This compares size, not location: both shapes are at the same scale, north up, centred on each other.
What happened to each town
-
1,028 ha0.8 %
Burnt area inside each municipality, from crossing the GWIS 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.
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) |
|---|---|---|---|---|---|
| 28 Mar | 32.5 °C | 23 % | 43 km/h | 0.0 mm | High 31 |
| 29 Mar | 31.5 °C | 26 % | 40 km/h | 0.0 mm | High 30 |
| 30 Mar | 32.4 °C | 27 % | 34 km/h | 0.0 mm | High 30 |
| 31 Mar | 32.1 °C | 30 % | 33 km/h | 0.0 mm | High 30 |
| 1 Apr | 32.1 °C | 33 % | 38 km/h | 0.0 mm | High 31 |
| 2 Apr | 32.4 °C | 28 % | 45 km/h | 0.0 mm | High 33 |
| 3 Apr | 31.2 °C | 31 % | 43 km/h | 0.0 mm | High 32 |
| 4 Apr | 32.0 °C | 27 % | 37 km/h | 0.0 mm | High 32 |
| 5 Apr | 32.7 °C | 25 % | 27 km/h | 0.0 mm | High 29 |
| 6 Apr | 32.9 °C | 29 % | 20 km/h | 0.0 mm | High 29 |
| 7 Apr | 33.6 °C | 31 % | 29 km/h | 0.0 mm | High 32 |
| 8 Apr after | 32.7 °C | 34 % | 29 km/h | 0.0 mm | High 31 |
| 9 Apr after | 35.1 °C | 28 % | 33 km/h | 0.0 mm | High 33 |
| 10 Apr after | 35.2 °C | 29 % | 29 km/h | 0.0 mm | High 32 |
| 11 Apr after | 35.0 °C | 30 % | 27 km/h | 0.0 mm | High 32 |
| 12 Apr after | 34.7 °C | 30 % | 28 km/h | 0.0 mm | High 32 |
| 13 Apr after | 34.8 °C | 33 % | 32 km/h | 0.0 mm | High 33 |
| 14 Apr after | 36.2 °C | 28 % | 26 km/h | 0.0 mm | High 34 |
| 15 Apr after | 36.5 °C | 25 % | 23 km/h | 0.0 mm | High 34 |
| 16 Apr after | 34.9 °C | 30 % | 32 km/h | 0.0 mm | High 36 |
| 17 Apr after | 35.0 °C | 33 % | 32 km/h | 0.0 mm | High 36 |
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 7 April 2023 the air beside the fire reached 76 µg/m³ of PM2.5. That day averaged 52: 3.4 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 · 31Every satellite heat detection, one by one, with time, satellite, power and coordinates.
| Date and time | Satellite | FRP (MW) | Lat | Lon |
|---|
Other fires nearby
- 14,912 haMae Suai แม่สรวย28 March 2026 · 20 days · 14 km away
- 12,779 haWiang Pa Pao เวียงป่าเป้า23 March 2026 · 28 days · 21 km away
- 15,402 haPhrao พร้าว26 March 2026 · 26 days · 24 km away
- 12,929 haWiang Pa Pao เวียงป่าเป้า22 March 2026 · 25 days · 30 km away
- 16,265 haWiang Pa Pao เวียงป่าเป้า17 March 2020 · 17 days · 32 km away
- 21,629 haMae Suai แม่สรวย8 April 2016 · 13 days · 34 km away
Frequently asked questions
- How long did the Phrao fire last?
- GWIS (Copernicus) dates it between 4 April 2023 and 7 April 2023: 4 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 1,021 hectares (10.2 km²). It is an estimate: official national figures may differ.
- Which municipalities burned?
- The fire only entered Phrao (1,028 ha, 0.8 %).
- What was the weather like?
- During the fire the temperature reached 33.6 °C, humidity dropped to 23 % and gusts hit 45 km/h. The fire danger index (FWI) reached 33, class High.
- Where does this data come from?
- From the GWIS (Copernicus) burnt perimeter, NASA FIRMS VIIRS hotspots and the administrative boundaries of Thailand (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: 199 · 191 · Emergency number and official warnings ›
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.
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: GWIS (Copernicus), rebuilt from heat detections rather than mapped on imagery.
- Dates from the perimeter: the VIIRS detections inside it did not change them. 31 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.
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 ADM2 (Creative Commons Attribution 3.0 Intergovernmental Organisations (CC BY 3.0 IGO)). 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.