From Next Day Wildfire to Next Days Wildfire: A New Multi-Continent Dataset of Active-Fire Spread for Sequence-to-Sequence Forecasting
Organizations: CENIA, Macul, Chile · Universidad de Chile, DCC, Santiago, Chile
Abstract
Benchmarks such as WildfireSpreadTS (WSTS) have enabled data-driven forecasting of wildfire spread from multimodal satellite time series, but they suffer from limitations: size restricts them to large fires that burn for weeks, and they are from similar environments. We introduce AFSeq, a multimodal dataset of 1,194 recent fire events (2023 to 2026) from 8 different countries across three regions, dominated by the short, small fires that existing benchmarks underrepresent. Our dataset is the largest and most diverse to date for time-series-based wildfire spread prediction. We also introduce UTAE-AR, an extension of a classical U-Net with Temporal Auto Encoder, enhanced with recurrent modules before the decoder. This allows the model to not only predict the next day but the whole sequence in an autoregressive way. Moreover, our model can feed its own predicted fire mask back one day at a time, producing the day-by-day forecasts that single-step models cannot. Our results show that UTAE-AR surpasses state-of-the-art on both WSTS, WSTS+ and AFSeq for next-day accuracy while having 21.5% of their parameters, and being able to predict confidently at a longer horizon.
Figures & tables
| AFSeq | WSTS [ 10 ] | WSTS+ [ 16 ] | |
| Coverage | |||
| Years covered | 2023-2026 | 2018-2021 | 2016-2023 |
| Regions | US, S. America, S. Europe | Western US | US |
| Size | |||
| Fire events | 607 | ||
| Total daily obs. | |||
| Model | Seq in | Seq out | Params | AP |
| Persistence | ✗ | ✗ | ||
| Single-frame | ||||
| U-Net | ✗ | ✗ | 0.43 M | |
| ConvNeXt | ✗ | ✗ | 203 M | |
| Temporal | ||||
| ConvLSTM | ✓ | ✗ | 0.19 M | |
| Model | Veg | Multi | All | Params |
| Res50-Unet [ 16 ] | 32.5 M | |||
| Res18-UTAE [ 16 ] | 14.7 M | |||
| UTAE-AR | 3.16 M |
| Model | Trained on | AFSeq | WSTS+ | Avg. |
| UTAE-AR | WSTS+ | .334 | ||
| AFSeq | .349 | |||
| Both | .381 | |||
| Res18-UTAE | WSTS+ | .294 | ||
| AFSeq | .311 | |||
| Both | .369 |
| Channel(s) | Product | Native res. | Cadence |
| elevation, slope, aspect | SRTM | 30 m | static |
| landcover (17 one-hot) | MODIS MCD12Q1 (IGBP) | 500 m | annual |
| ndvi, evi | MODIS MOD13Q1 | 250 m | 16 d |
| et | MODIS MOD16A2 | 500 m | 8 d |
| lst | MODIS MYD11A1 (Aqua) * | 1 km | daily |
| dew, rh, wind_speed, wind_dir, pressure | ERA5-Land hourly | 9 km | daily |
| Region | Start year | ||||||||
| Seed | Split | S. Am. | S. Eur. | U.S. | 2023 | 2024 | 2025 | 2026 | |
| 5 | Train | 835 | 317 | 223 | 295 | 89 | 336 | 357 | 53 |
| Val | 179 | 68 | 48 | 63 | 10 | 80 | 79 | 10 | |
| Test | 180 | 68 | 48 | 64 | 17 | 77 | 73 | 13 | |
| 7 | Train | 835 | 317 | 223 | 295 | 77 | 351 | 356 | 51 |
| Val | 179 | 68 | 48 | 63 | 18 | 71 | 77 | 13 | |
| Region | Events | Area (ha) | Fire days | Fire px | Persistence |
| median | median (max) | median | AP | ||
| South America | 453 | 1,088 | 10 (49) | 7,017 | 0.128 |
| S. Europe | 319 | 625 | 2 (25) | 1,969 | 0.095 |
| United States | 422 | 1,327 | 5 (42) | 4,227 | 0.122 |
| Model | Params (M) | Predicted days | GFLOPs | Latency (ms) | ms / day | Peak mem. (MiB) |
| UTAE-AR (ours) | 3.16 | 5 | 124.5 | 21.3 | 4.3 | 139 |
| Res18-UTAE | 14.7 | 1 | 11.4 | 14.5 | 14.5 | 120 |
| UTAE | 0.89 | 1 | 38.8 | 8.2 | 8.2 | 210 |
| fold 0 | fold 1 | fold 2 | fold 3 | mean std | |
| Persistence | 0.134 | 0.067 | 0.182 | 0.233 | 0.154 0.071 |
| UTAE-AR, Veg | 0.378 | 0.309 | 0.495 | 0.539 | 0.429 0.105 |
| UTAE-AR, Multi | 0.410 | 0.318 | 0.508 | 0.549 | 0.445 0.104 |
| UTAE-AR, All | 0.406 | 0.311 | 0.501 | 0.550 | 0.441 0.106 |
| Model | partition 5 | partition 7 | partition 23 | mean std |
| Persistence | 0.120 | 0.114 | 0.139 | 0.124 0.011 |
| U-Net | 0.216 | 0.232 | 0.278 | 0.242 0.032 |
| ConvNeXt | 0.215 | 0.258 | 0.289 | 0.254 0.037 |
| ConvLSTM | 0.273 | 0.305 | 0.328 | 0.302 0.028 |
| UTAE | 0.268 | 0.290 | 0.336 | 0.298 0.035 |
| Res18-UTAE | 0.309 | 0.320 | 0.335 | 0.321 0.013 |
| Fold | Train years | Val | Test | Persistence | UTAE-AR |
| 0 | 2020, 2021 | 2019 | 2018 | 0.192 | 0.511 |
| 1 | 2019, 2021 | 2020 | 2018 | 0.192 | 0.495 |
| 2 | 2019, 2020 | 2021 | 2018 | 0.192 | 0.485 |
| 3 | 2020, 2021 | 2018 | 2019 | 0.112 | 0.374 |
| 4 | 2018, 2021 | 2020 | 2019 | 0.112 | 0.357 |
| 5 | 2018, 2020 | 2021 | 2019 | 0.112 | 0.356 |
| Held out | Model | LORO | Standard split | |
| South America | Persistence | 0.128 | – | – |
| UTAE-AR (ours) | 0.206 | 0.364 0.051 | ||
| Res18-UTAE | 0.181 | 0.322 0.091 | ||
| S. Europe | Persistence | 0.095 | – | – |
| UTAE-AR (ours) | 0.243 | 0.279 0.053 | ||
| Res18-UTAE | 0.193 | 0.202 0.017 |
| Trained on | Future covariates at inference | |||||
| Ground-truth future covariates | Ground-truth future covariates | 0.368 | 0.318 | 0.274 | 0.236 | 0.222 |
| GFS forecast issued on day | 0.368 | 0.268 | 0.236 | 0.198 | 0.192 | |
| Day- values frozen | 0.368 | 0.222 | 0.154 | 0.118 | 0.104 | |
| GFS forecast | GFS forecast issued on day | 0.360 | 0.286 | 0.243 | 0.200 | 0.181 |
| Ground-truth future covariates | 0.360 | 0.281 | 0.229 | 0.187 | 0.168 | |
| Day- values frozen | 0.360 | 0.192 | 0.126 | 0.090 | 0.076 |
Wildfire Forecasting
Wildfire forecasting predicts where fires will start, how they will spread, and their likely intensity or impacts using environmental and fire observations.
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