Forecast-independent observed truth from the locked P90/EHD/episode definitions. National domain = all valid VnGAD cells (region 0–7); regional rows exclude the unassigned region 0. Episodes detected on the continuous daily series with a boundary buffer.
| region | n_cells | mean EHD freq | episodes/yr | mean duration (d) | mean severity (degC·d) |
| region | n_cells | mean_ehd_freq | episodes_per_year_mean | mean_duration | mean_severity |
| 0 | 45 | 0.1027 | 8.397 | 3.413 | 3.124 |
| 1 | 51 | 0.0935 | 8.217 | 3.168 | 3.068 |
| 2 | 105 | 0.0929 | 8.215 | 3.082 | 3.782 |
| 3 | 37 | 0.0956 | 9.005 | 3.036 | 3.750 |
| 4 | 88 | 0.1076 | 9.616 | 3.343 | 4.325 |
| 5 | 63 | 0.0969 | 7.970 | 3.477 | 2.889 |
| 6 | 96 | 0.1078 | 8.117 | 3.620 | 3.078 |
| 7 | 101 | 0.1064 | 7.649 | 3.514 | 2.084 |
| ALL | 586 | 0.1013 | 8.349 | 3.356 | 3.245 |
Sources: data/processed/obs_climatology_2003_2022.nc, outputs/metrics/obs_episode_catalog_2003_2022.csv, obs_climatology_by_region.csv.