Burned area
satellite only21,340ha
Union of 2 GWIS (Copernicus) perimeters: overlapping areas count once.
- Source
- GWIS (Copernicus)
- Date
- 7 Apr 2023 – 20 Apr 2023
+− cross-check
No official record is matched to this page to compare it with.
IN · India · –
Longtharai Valley fire, April 2023 Longtharai Valley, Kanchanpur, West Phaileng
Out · last measured on 20 Apr 2023
The fire started on 7 April 2023 in Longtharai Valley, India, and satellites saw it burning for 14 days. Copernicus’s global GWIS system rebuilt a burnt perimeter of 21,340 hectares from heat detections, spread across 4 municipalities.
It is the 2th largest in Tripura since 2016 (of 11 with a page). The largest in India in 2023, of 22.
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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 only14days
7 Apr 2023 to 20 Apr 2023: first and last day with fire on the page.
- Source
- GWIS (Copernicus) · NASA FIRMS · VIIRS
- Date
- 7 Apr 2023 – 20 Apr 2023
+− 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 only7 Apr 2023
First day with fire seen by the satellites or the perimeter.
- Source
- GWIS (Copernicus) · NASA FIRMS · VIIRS
- Date
- 7 Apr 2023
+− cross-check
No official record is matched to this page, so the alert time and the cause are not known here.
Danger at the start
model9.4FWI · low
Fire Weather Index (Canadian system) computed by WorldFires for the day the fire started. Consecutive days without rain before: 1.
- Source
- WorldFires calculation (Canadian FWI system)
- Date
- 7 Apr 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
model38.7°C · 25% RH
High of 38.7 °C and minimum humidity of 25% on 14 April 2023; gusts of 42 km/h on 20 April 2023.
- Source
- weather model at the fire’s grid cell
- Date
- 7 Apr 2023 – 20 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.
Living inside
model≈ 3,400people
Estimated residents inside the perimeter and 15 ha of built-up area (100 m grid, epoch 2025).
- Source
- GHSL R2023A · JRC
- Date
- calculated on 24 October 2026
+− cross-check
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.
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 GHSLPopulation and built-up area computed
-
· reconstructed weatherWeather and FWI computed from the ERA5 reanalysis
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
- 21,363 ha
- Dates
- 7 Apr 2023 – 20 Apr 2023
- Name
- Longtharai Valley
- Official record
- —
Versioned permanent link
https://worldfires.org/en/fire/longtharai-valley-2023-04?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 longtharai-valley-2023-04.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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 2023-04-07 | 0 | 0 | 35.4 | 20.8 | 28 | 7.9 | 22.3 | 0 | 9.4 | bajo | 1 |
| 2023-04-08 | 0 | 0 | 35.8 | 21.3 | 23 | 9.2 | 26.6 | 0 | 13.5 | moderado | 1 |
| 2023-04-09 | 0 | 0 | 36.7 | 20.9 | 26 | 11 | 28.8 | 0 | 15.6 | moderado | 1 |
| 2023-04-10 | 0 | 0 | 36.8 | 22 | 28 | 10.9 | 29.2 | 0 | 16.8 | moderado | 1 |
| 2023-04-11 | 0 | 0 | 36.7 | 22.4 | 29 | 10.8 | 27.4 | 0 | 17.9 | moderado | 1 |
| 2023-04-12 | 0 | 0 | 37.7 | 22.6 | 24 | 9.5 | 25.9 | 0 | 18.9 | moderado | 1 |
| 2023-04-13 | 0 | 0 | 37.8 | 23.5 | 27 | 12.6 | 25.6 | 0 | 22 | alto | 1 |
| 2023-04-14 | 0 | 0 | 38.7 | 23.5 | 25 | 10.8 | 28.4 | 0 | 22.3 | alto | 1 |
| 2023-04-15 | 0 | 0 | 38.4 | 24 | 30 | 11.5 | 30.2 | 0 | 24 | alto | 1 |
| 2023-04-16 | 0 | 0 | 38.6 | 24.5 | 31 | 14.1 | 36 | 0 | 26.9 | alto | 1 |
| 2023-04-17 | 0 | 0 | 37.3 | 26.4 | 42 | 12.4 | 32.8 | 3.4 | 7.9 | bajo | 1 |
| 2023-04-18 | 0 | 0 | 37.4 | 25.8 | 40 | 10.7 | 28.1 | 0 | 15.4 | moderado | 1 |
| 2023-04-19 | 0 | 0 | 36.6 | 26.1 | 43 | 13.3 | 37.8 | 0 | 17.3 | moderado | 1 |
| 2023-04-20 | 0 | 0 | 36.7 | 25.7 | 44 | 15 | 41.8 | 1.2 | 15.2 | moderado | 1 |
| 2023-04-21 | 0 | 0 | 32.8 | 21.5 | 56 | 18.1 | 45 | 10.4 | 3 | muy_bajo | 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
We have the GWIS perimeter for this fire, but the VIIRS sensors did not capture it in enough detail: no day-by-day evolution, but the split by municipality is there.
- Burnt area
- 21,340ha
- GWIS perimeter (Copernicus)
- Duration
- 14days
- 7 Apr 2023 – 20 Apr 2023
- Municipalities hit
- 4
- subdistricts
- Started on
- 7 Apr
- 2023
- Danger at start
- 9
- Low · FWI index
Where it burned
The weather it burned in
39°high
42km/h · peak gust
23%lowest humidity
It had gone one day without rain (1 mm or more) when it started. Rain came after the fire: 10.4 mm on 21 Apr.
This area had burned before
94% of the perimeter overlaps earlier fires recorded since 2016: 5,917 ha in 2016, 5,766 ha in 2017, 8,399 ha in 2018, 7,461 ha in 2019, 10,246 ha in 2020, 12,183 ha in 2021, 7,299 ha in 2022. Part of it burned more than once, so the yearly figures add up to more than the 20,086 ha that had burned before.
- 4,177 ha Longtharai Valley fire, March 2020 10,443 ha in total; the hectares shown are those it shares with this fire
- 1,419 ha Longtharai Valley fire, April 2016 5,038 ha in total; the hectares shown are those it shares with this fire
- 400 ha Zawlnuam fire, March 2021 8,761 ha in total; the hectares shown are those it shares with this fire
- 290 ha Zawlnuam fire, March 2019 9,469 ha in total; the hectares shown are those it shares with this fire
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 town
-
Longtharai Valley where it started13,234 ha14 %
-
5,941 ha7.9 %
-
54 ha0.0 %
-
41 ha0.0 %
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 area15 ha
Residents≈ 3,400
Inside the perimeter there were about 15 hectares of built-up land and about 3,400 residents (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) |
|---|---|---|---|---|---|
| 7 Apr | 35.4 °C | 28 % | 22 km/h | 0.0 mm | Low 9 |
| 8 Apr | 35.8 °C | 23 % | 27 km/h | 0.0 mm | Moderate 14 |
| 9 Apr | 36.7 °C | 26 % | 29 km/h | 0.0 mm | Moderate 16 |
| 10 Apr | 36.8 °C | 28 % | 29 km/h | 0.0 mm | Moderate 17 |
| 11 Apr | 36.7 °C | 29 % | 27 km/h | 0.0 mm | Moderate 18 |
| 12 Apr | 37.7 °C | 24 % | 26 km/h | 0.0 mm | Moderate 19 |
| 13 Apr | 37.8 °C | 27 % | 26 km/h | 0.0 mm | High 22 |
| 14 Apr | 38.7 °C | 25 % | 28 km/h | 0.0 mm | High 22 |
| 15 Apr | 38.4 °C | 30 % | 30 km/h | 0.0 mm | High 24 |
| 16 Apr | 38.6 °C | 31 % | 36 km/h | 0.0 mm | High 27 |
| 17 Apr | 37.3 °C | 42 % | 33 km/h | 3.4 mm | Low 8 |
| 18 Apr | 37.4 °C | 40 % | 28 km/h | 0.0 mm | Moderate 15 |
| 19 Apr | 36.6 °C | 43 % | 38 km/h | 0.0 mm | Moderate 17 |
| 20 Apr | 36.7 °C | 44 % | 42 km/h | 1.2 mm | Moderate 15 |
| 21 Apr after | 32.8 °C | 56 % | 45 km/h | 10.4 mm | Very low 3 |
Its twins: fires that started in the same weather
It started with an FWI of 9.4, a minimum humidity of 28% and 1 day without rain. Fires in the area that started in weather like this since 2016: 18.
FWI at the start
9.4
Minimum humidity
28 %
Days without rain
1
this fire
chosen twins
rest of the area
Almost identicalSimilar
Outlines of the closest twins
This fire · Longtharai Valley fire, April 2023
21,340 ha
14 days
FWI 9.4
Min. humidity 28 %
Kanchanpur fire, March 2019
5,654 ha
3 days
FWI 7.1
Min. humidity 30 %
25 km away, in 2019
First rain (1 mm or more) after it ended: 1.8 mm on 27 Mar.
Jirang fire, April 2017
6,436 ha
7 days
FWI 14.4
Min. humidity 28 %
242 km away, in 2017
First rain (1 mm or more) after it ended: 7.5 mm on 16 Apr.
Matupi fire, April 2022
2,546 ha
8 days
FWI 14.8
Min. humidity 28 %
247 km away, in 2022
First rain (1 mm or more) after it ended: 1.1 mm on 14 Apr.
Falam fire, March 2019
2,393 ha
20 days
FWI 9.5
Min. humidity 33 %
205 km away, in 2019
First rain (1 mm or more) after it ended: 7.1 mm on 2 Apr.
Chawngte fire, March 2019
24,749 ha
16 days
FWI 15.0
Min. humidity 32 %
161 km away, in 2019
First rain (1 mm or more) after it ended: 10.2 mm on 2 Apr.
What happened to them
- 9 days
- median duration
- 4,418 ha
- median area
- 17 %
- went past 10,000 ha
- 2.2 mm
- rain at the end (median; 15 of 18 had it)
It was 4.8 times larger than the median of its twins and lasted 14 days, against 9 days.
Only 1 of its 18 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 3 of 18, 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 2.2 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
10.4 mmfirst rain
21 Aprthe day after it ended
42km/h · max. gust
It was considered over on 20 Apr, and on 21 Apr 10.4 mm fell. We do not know whether the rain or the firefighters put it out. Twins with rain when they ended: 15 of 18, with a median of 2.2 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 · 31 Mar 2023
After · 27 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 12 April 2023 the air beside the fire reached 622 µg/m³ of PM2.5. That day averaged 290: 19 times the WHO daily guideline (15).
PM2.5 peak622 µg/m³
Days over the guideline19 days
PM10890 µg/m³
Optical depth1.86
WHO 15
5 Apr9 Apr13 Apr17 Apr21 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)
Other fires nearby
- 10,443 haLongtharai Valley25 March 2020 · 8 days · 7 km away
- 15,580 haAmbassaApril 2026 · 16 days · 11 km away
- 15,012 haGandacherraApril 2026 · 22 days · 22 km away
- 15,481 haLongtharai ValleyMarch 2021 · 10 days · 24 km away
- 24,186 haGandacherraMarch 2020 · 12 days · 25 km away
- 9,469 haZawlnuamMarch 2019 · 6 days · 27 km away
Frequently asked questions
- How long did the Longtharai Valley fire last?
- GWIS (Copernicus) dates it between 7 April 2023 and 20 April 2023: 14 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 21,340 hectares (213.4 km²). It is an estimate: official national figures may differ.
- Which municipalities burned?
- The fire entered 4 municipalities: Longtharai Valley (13,234 ha, 14 %); Kanchanpur (5,941 ha, 7.9 %); West Phaileng (54 ha, 0.0 %); Zawlnuam (41 ha, 0.0 %).
- What was the weather like?
- During the fire the temperature reached 38.7 °C, humidity dropped to 23 % and gusts hit 42 km/h. The fire danger index (FWI) reached 27, class High.
- Where does this data come from?
- From the GWIS (Copernicus) burnt perimeter, NASA FIRMS VIIRS hotspots and the administrative boundaries of India (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: 18. Their median duration was 9 days and their median area 4,418 ha; 17 % went past 10,000 ha. Only 1 of its 18 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 3 of 18, 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 2.2 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: 112 · 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.
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; 2 polygons grouped in this page.
- Dates from the perimeter: the VIIRS detections inside it did not change them. No 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 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.