The Precipitation Variation KPI measures the percentage change in precipitation in the study area relative to the climatological reference period 1961–1990 (WMO baseline). The indicator compares the average precipitation of the last 3 years with the historical baseline and with other reference periods (previous 3-year period, 10 years ago, 50 years ago), providing a multi-scale reading of local rainfall trends.
Precipitation is a fundamental driver of ecosystem health: a significant decline relative to the historical norm signals increasing aridity that can compromise the survival of plant species, reduce streamflow, increase vulnerability to wildfires and deteriorate habitat quality. The indicator is direct (not inverted): a higher value (less negative or positive) indicates precipitation equal to or above baseline, a condition considered more favourable for biodiversity.
Precipitation data come from the Open-Meteo Historical Weather API (~10 km resolution, ERA5-Land) for the period 1940–present.
Definition of calculation periods (current year = X):
| Period | Years included | Description |
|---|---|---|
ref_mean | 1961–1990 | WMO climatological baseline |
last_3y_mean | X-3, X-2, X-1 | Most recent 3-year period (highlighted value) |
ref_3y_mean | X-6, X-5, X-4 | Previous 3-year period (short-term comparison) |
ref_10y_mean | X-13, X-12, X-11 | 3-year period 10 years ago (medium-term comparison) |
ref_50y_mean | X-60, …, X-51 | Decade 50 years ago (long-term comparison) |
Highlighted value formula:
rain_kpi = 100 × (last_3y_mean − ref_mean) / ref_mean
Units:
Comparisons with ref_3y_mean, ref_10y_mean and ref_50y_mean are also displayed to show the evolution of rainfall trends.
| Code | Name | Provider | Resolution | Availability |
|---|---|---|---|---|
WRD_OPNMT_99 | Open-Meteo Historical Weather | Open-Meteo / ERA5 | ~10 km | 1940 — present |
| Indicator | Unit | Range | Inverted |
|---|---|---|---|
rain_rank | — | [0, 1, 2, 3, 4, 5] | No |
Inverted = No: a higher value indicates precipitation closer to or above the historical baseline, a condition considered more favourable for the ecosystem.
| Level | Rank | Interpretation |
|---|---|---|
| A (Excellent) | 5 | Precipitation at or above baseline; no rainfall deficit |
| B (Good) | 4 | Slight decline from norms; negligible ecosystem impact |
| C (Moderate) | 3 | Moderate reduction; possible seasonal water stress |
| D (Poor) | 2 | Significant reduction; drought risk and biodiversity decline |
| E (Critical) | 1 | Strong rainfall deficit; severe impact on habitats and species |
last_3y_mean excludes the current year to avoid bias from incomplete seasonsrain_rank
Precipitation data from Open-Meteo Historical Weather (~10 km, ERA5-Land), 1940–present. Current year = X. Calculation periods: ref_mean (1961–1990, WMO baseline), last_3y_mean (X-3, X-2, X-1), ref_3y_mean (X-6, X-5, X-4), ref_10y_mean (X-13, X-12, X-11), ref_50y_mean (X-60, …, X-51). Formula: rain_kpi = 100 × (last_3y_mean − ref_mean) / ref_mean. Absolute precipitation in cm (from mm ÷ 10), variations in %. Direct indicator (not inverted): higher values = better rainfall condition.