Soil Moisture & Temperature
How the Isle of Man's soil moisture and temperature have varied from 2000 to 2025, derived from the ERA5-Land reanalysis dataset at ~9 km resolution.
Soil moisture is measured as volumetric water content (m³/m³) at three depths: surface (0–7 cm), root zone (7–28 cm), and deep (28–100 cm). Soil temperature is measured at the surface and root zone.
More from Biosphere
Soil Moisture by Depth (Last 3 Years)
Monthly mean volumetric water content (m³/m³) at three soil depths. Higher values indicate wetter soil; values above 0.4 suggest near-saturation.
Seasonal Averages (2000–2025)
Mean soil moisture and temperature by season, averaged across all years. Winter soils are wettest; summer soils are driest and warmest.
Annual Mean Soil Moisture Trend
Annual mean surface soil moisture (0–7 cm) from 2000 to 2025. Shaded band shows min–max range.
Soil Temperature vs Moisture
Monthly soil temperature (surface, 0–7 cm) plotted against moisture content. Warmer months tend to have drier soils due to increased evapotranspiration.
Methodology & Data Source
Soil moisture and temperature data from the ERA5-Land reanalysis dataset, produced by the European Centre for Medium-Range Weather Forecasts (ECMWF) and distributed by the Copernicus Climate Change Service. Data is accessed via the Open-Meteo Archive API.
ERA5-Land provides hourly land-surface variables at ~9 km resolution globally, from 1950 to near real-time. It assimilates satellite observations and surface measurements into a physical land-surface model, producing consistent gridded estimates of soil state. Values shown here are daily means aggregated to monthly, annual, and seasonal summaries.
Soil moisture is expressed as volumetric water content (m³ of water per m³ of soil). Typical values on the Isle of Man range from 0.25–0.45 m³/m³. Values above 0.4 indicate near-saturation (common in winter); below 0.2 indicates dry conditions (rare on the IoM). Soil temperature reflects heat stored in the ground, which lags behind air temperature and moderates root-zone conditions for plants.
Important caveats: ERA5-Land is a model-based reanalysis, not direct measurement. The ~9 km grid cell covers most of the island and may not capture local microclimates. Peat soils, coastal areas, and upland regions will differ from the grid-cell average. For precise site-specific data, in-situ sensors are required.
Muñoz Sabater, J., (2019): ERA5-Land hourly data from 1950 to present. Copernicus Climate Change Service (C3S) Climate Data Store (CDS). | Generated 25/03/2026.
Why does soil moisture matter?
Soil moisture controls plant growth, flood risk, and ecosystem health. Too wet and soils become waterlogged, limiting root oxygen. Too dry and plants struggle to absorb nutrients. The IoM's maritime climate keeps soils relatively moist year-round.
Soil temperature & frost
Soil temperature affects seed germination, microbial activity, and root growth. Frost days (soil temp below 0°C) can damage shallow-rooted plants and slow decomposition. The IoM's Gulf Stream influence means soil frost is relatively uncommon compared to inland Britain.
Three soil depths
Surface (0–7 cm) responds quickly to rainfall and evaporation. Root zone (7–28 cm) is where most plant roots absorb water. Deep soil (28–100 cm) changes slowly and reflects longer-term groundwater trends. Deeper layers are buffered against daily weather.