Burned area
satellite only1,293ha
Perimeter published by GWIS (Copernicus).
- Source
- GWIS (Copernicus)
- Date
- 27 Mar 2023 – 2 Apr 2023
+− cross-check
No official record is matched to this page to compare it with.
TH · Thailand · –
Mae Ai fire, 27 March 2023 แม่อาย · Mae Suai, Mae Ai
Out · last detection 1 Apr 2023, 18:50 UTC
The fire started on 27 March 2023 in Mae Ai, Thailand, and satellites saw it burning for 7 days. Copernicus’s global GWIS system rebuilt a burnt perimeter of 1,293 hectares from heat detections, spread across 2 municipalities.
It is the 201th largest in Chiang Mai Province since 2016 (of 319 with a page). Number 243 in Thailand in 2023, of 369.
The power measured by the satellite is low (11.6 MW in the strongest hotspot), more typical of grass or stubble burning, or a slow surface fire, than of a large crown fire.
Use this data
Compare with…
Use this data
Fire page data · version 2026-10-26matches 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 only7days
27 Mar 2023 to 2 Apr 2023: first and last day with fire on the page.
- Source
- GWIS (Copernicus) · NASA FIRMS · VIIRS
- Date
- last detection: 1 Apr 2023, 18:50 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 only27 Mar 2023
First day with fire seen by the satellites or the perimeter.
- Source
- GWIS (Copernicus) · NASA FIRMS · VIIRS
- Date
- 27 Mar 2023
+− cross-check
No official record is matched to this page, so the alert time and the cause are not known here.
Hotspots
satellite only26
VIIRS detections at 375 m. Most intense hotspot: 12 MW.
- Source
- NASA FIRMS · VIIRS (Suomi NPP)
- Date
- 27 Mar 2023 – 2 Apr 2023
+− 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 only22MW
Total radiative power on 27 March 2023; hotspots that day: 3.
- Source
- NASA FIRMS · VIIRS (FRP)
- Date
- 27 Mar 2023
+− 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
model25.1FWI · high
Fire Weather Index (Canadian system) computed by WorldFires for the day the fire started. Consecutive days without rain before: 5.
- Source
- WorldFires calculation (Canadian FWI system)
- Date
- 27 Mar 2023, 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
model34.8°C · 21% RH
High of 34.8 °C and minimum humidity of 21% on 28 March 2023; gusts of 41 km/h on 2 April 2023.
- Source
- weather model at the fire’s grid cell
- Date
- 27 Mar 2023 – 2 Apr 2023
- 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
-
logLast day with fire: 31 March 2023 → 2 April 2023.
-
· reconstructed GHSLPopulation and built-up area computed
What was saved on 26 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
- 1,293 ha
- Dates
- 27 Mar 2023 – 2 Apr 2023
- Name
- Mae Ai
- Official record
- —
Versioned permanent link
https://worldfires.org/en/fire/mae-ai-2023-03-3?v=2026-10-26A 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 mae-ai-2023-03-3.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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 2023-03-27 | 3 | 22 | 33.2 | 15.7 | 28 | 7.9 | 24.8 | 0 | 25.1 | alto | 1 |
| 2023-03-28 | 11 | 15 | 34.8 | 16.2 | 21 | 12.8 | 39.2 | 0 | 31 | alto | 1 |
| 2023-03-29 | 3 | 7 | 32.6 | 17.7 | 27 | 11.9 | 38.2 | 0 | 30.9 | alto | 1 |
| 2023-03-30 | 2 | 3 | 33.9 | 17.3 | 25 | 9.7 | 30.6 | 0 | 29.9 | alto | 1 |
| 2023-03-31 | 3 | 8 | 34.4 | 16.4 | 24 | 9.3 | 30.2 | 0 | 30.3 | alto | 1 |
| 2023-04-01 | 4 | 11 | 34.8 | 17.2 | 27 | 10.2 | 33.8 | 0 | 31.7 | alto | 1 |
| 2023-04-02 | 0 | 0 | 33.8 | 19.6 | 26 | 13.2 | 41 | 0 | 34.8 | alto | 1 |
| 2023-04-03 | 0 | 0 | 33.1 | 18.8 | 27 | 12.8 | 40.7 | 0 | 34.6 | alto | 0 |
| 2023-04-04 | 0 | 0 | 34.5 | 18 | 22 | 12.3 | 38.9 | 0 | 34.8 | alto | 0 |
| 2023-04-05 | 0 | 0 | 34.7 | 16 | 19 | 7.1 | 27 | 0 | 31.8 | alto | 0 |
| 2023-04-06 | 0 | 0 | 34.8 | 15.2 | 25 | 6.8 | 18.4 | 0 | 32.1 | alto | 0 |
| 2023-04-07 | 0 | 0 | 35.6 | 16.7 | 26 | 6.5 | 20.2 | 0 | 32.3 | alto | 0 |
| 2023-04-08 | 0 | 0 | 35.9 | 19.5 | 28 | 7.1 | 23.8 | 0 | 32.9 | alto | 0 |
| 2023-04-09 | 0 | 0 | 37.4 | 21.1 | 24 | 7.1 | 23.8 | 0 | 33.3 | alto | 0 |
| 2023-04-10 | 0 | 0 | 37.6 | 19.5 | 21 | 7.1 | 25.6 | 0 | 33.8 | alto | 0 |
| 2023-04-11 | 0 | 0 | 36.8 | 19 | 25 | 8.1 | 29.9 | 0 | 35.1 | alto | 0 |
| 2023-04-12 | 0 | 0 | 36.9 | 18.6 | 22 | 6.9 | 25.9 | 0 | 34.5 | alto | 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: GWIS (Copernicus), 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
- 1,293ha
- GWIS perimeter (Copernicus)
- Duration
- 7days
- 27 Mar 2023 – 2 Apr 2023
- Municipalities hit
- 2
- districts
- Started on
- 27 Mar
- 2023
- Heat detections
- 26
- in a single hotspot: 12 MW
- Danger at start
- 25
- High · FWI index
- Average daily power
- 11MW
- detected power per day, on average
Where it burned
HOTSPOTS BY DAY
27 Mar2 Apr
1 Apr 2023
How it evolved, day by day
27 Mar
29 Mar
31 Mar
Fire radiative power detected each day, in megawatts, and number of hotspots. The magenta bar marks the peak day.
The weather it burned in
35°high
41km/h · peak gust
21%lowest humidity
It had gone 5 days without rain (1 mm or more) when it started.
This area had burned before
74% of the perimeter overlaps earlier fires recorded since 2016: 879 ha in 2016, 347 ha in 2019, 318 ha in 2020, 290 ha in 2021. Part of it burned more than once, so the yearly figures add up to more than the 955 ha that had burned before.
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
-
Mae Suai แม่สรวย947 ha reached on 28 Mar0.7 %
-
354 ha reached on 27 Mar0.4 %
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.
People and buildings inside the perimeter
GHSL 2025Built-up area< 0.1 ha
Residents< 20
Inside the perimeter there was no noticeable built-up land and almost nobody lived there (GHSL 2025, 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. The GHSL 2025 epoch is a projection made from 2020 and earlier data.
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) |
|---|---|---|---|---|---|
| 27 Mar | 33.2 °C | 28 % | 25 km/h | 0.0 mm | High 25 |
| 28 Mar | 34.8 °C | 21 % | 39 km/h | 0.0 mm | High 31 |
| 29 Mar | 32.6 °C | 27 % | 38 km/h | 0.0 mm | High 31 |
| 30 Mar | 33.9 °C | 25 % | 31 km/h | 0.0 mm | High 30 |
| 31 Mar | 34.4 °C | 24 % | 30 km/h | 0.0 mm | High 30 |
| 1 Apr | 34.8 °C | 27 % | 34 km/h | 0.0 mm | High 32 |
| 2 Apr | 33.8 °C | 26 % | 41 km/h | 0.0 mm | High 35 |
| 3 Apr after | 33.1 °C | 27 % | 41 km/h | 0.0 mm | High 35 |
| 4 Apr after | 34.5 °C | 22 % | 39 km/h | 0.0 mm | High 35 |
| 5 Apr after | 34.7 °C | 19 % | 27 km/h | 0.0 mm | High 32 |
| 6 Apr after | 34.8 °C | 25 % | 18 km/h | 0.0 mm | High 32 |
| 7 Apr after | 35.6 °C | 26 % | 20 km/h | 0.0 mm | High 32 |
| 8 Apr after | 35.9 °C | 28 % | 24 km/h | 0.0 mm | High 33 |
| 9 Apr after | 37.4 °C | 24 % | 24 km/h | 0.0 mm | High 33 |
| 10 Apr after | 37.6 °C | 21 % | 26 km/h | 0.0 mm | High 34 |
| 11 Apr after | 36.8 °C | 25 % | 30 km/h | 0.0 mm | High 35 |
| 12 Apr after | 36.9 °C | 22 % | 26 km/h | 0.0 mm | High 34 |
Its twins: fires that started in the same weather
It started with an FWI of 25.1, a minimum humidity of 28% and 5 days without rain. Fires in the area that started in weather like this since 2016: 80.
FWI at the start
25.1
Minimum humidity
28 %
Days without rain
5
this fire
chosen twins
rest of the area
Almost identicalSimilar
Outlines of the closest twins
This fire · Mae Ai fire, 27 March 2023
1,293 ha
7 days
FWI 25.1
Min. humidity 28 %
Mae Ai fire, April 2018
1,333 ha
4 days
FWI 25.0
Min. humidity 27 %
10 km away, in 2018
First rain (1 mm or more) after it ended: 1.5 mm on 25 Apr.
Phu Sang fire, March 2025
1,431 ha
5 days
FWI 26.1
Min. humidity 28 %
115 km away, in 2025
First rain (1 mm or more) after it ended: 1.0 mm on 8 Mar.
Mongping fire, April 2017
4,396 ha
5 days
FWI 24.5
Min. humidity 27 %
96 km away, in 2017
First rain (1 mm or more) after it ended: 7.3 mm on 13 Apr.
Mueang Mae Hong Son fire, March 2021
4,556 ha
9 days
FWI 25.9
Min. humidity 28 %
156 km away, in 2021
First rain (1 mm or more) after it ended: none in the following ten days.
Mueang Chiang Rai fire, April 2016
3,590 ha
22 days
FWI 29.3
Min. humidity 28 %
24 km away, in 2016
First rain (1 mm or more) after it ended: 1.4 mm on 29 Apr.
What happened to them
- 9 days
- median duration
- 1,913 ha
- median area
- 99 %
- went past 1,000 ha
- 2.1 mm
- rain at the end (median; 36 of 80 had it)
It burned an area similar to its twins (1,293 ha against a median of 1,913 ha) and lasted 7 days, against 9 days.
In 44 of 80, 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 2.1 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
—first rain
—no rain in ten days
41km/h · max. gust
It was considered over on 2 Apr, and not even 1 mm fell in the following ten days: it went out without rain. Twins with rain when they ended: 36 of 80, with a median of 2.1 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 · 20 Mar 2023
After · 9 Apr 2023
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.
The smoke
CAMS · CopernicusOn 27 March 2023 the air beside the fire reached 185 µg/m³ of PM2.5. That day averaged 99: 6.6 times the WHO daily guideline (15).
PM2.5 peak185 µg/m³
Days over the guideline10 days
PM10265 µg/m³
Optical depth1.53
WHO 15
25 Mar27 Mar29 Mar31 Mar2 Apr
Good
Fair
Moderate
Poor
Very poor
Extremely poor
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 · 26Every 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
- 21,629 haMae Suai แม่สรวย1 April 2016 · 27 days · 18 km away
- 10,480 haMae Suai แม่สรวย13 March 2019 · 24 days · 21 km away
- 10,342 haMae Lao แม่ลาวMarch 2026 · 28 days · 24 km away
- 12,562 haPhan พานMarch 2026 · 29 days · 26 km away
- 13,344 haMae Suai แม่สรวย25 March 2026 · 30 days · 38 km away
- 17,275 haMae Chan แม่จันMarch 2023 · 31 days · 40 km away
Frequently asked questions
- How long did the Mae Ai fire last?
- According to the heat detections seen by satellite inside the perimeter, it burned from 27 March 2023 to 2 April 2023 (7 days). The perimeter dates it from 27 March 2023 to 31 March 2023.
- How much area did it burn?
- The perimeter GWIS (Copernicus) rebuilt from heat detections is 1,293 hectares (12.9 km²). It is an estimate: official national figures may differ.
- Which municipalities burned?
- The fire entered 2 municipalities: Mae Suai (947 ha, 0.7 %); Mae Ai (354 ha, 0.4 %).
- What was the weather like?
- During the fire the temperature reached 34.8 °C, humidity dropped to 21 % and gusts hit 41 km/h. The fire danger index (FWI) reached 35, 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.
- 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: 80. Their median duration was 9 days and their median area 1,913 ha; 99 % went past 1,000 ha. In 44 of 80, 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 2.1 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: 199 · 191 · Emergency number and official warnings
Satellite cross-check
History of this page · 1 Changes in area, dates, name, official record or merged pages, compared every night since 24 October 2026.
- Last day with fire: 31 March 2023 → 2 April 2023.
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: GWIS (Copernicus), rebuilt from heat detections rather than mapped on imagery.
- Dates adjusted with the VIIRS detections inside the perimeter, which said 27 March 2023 to 31 March 2023. 26 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 2025, 100 m cells), summed inside the perimeter: an estimate of what was there, not a damage count.
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.