Land Surface Temperature
Temperature trends on the Isle of Man from 2000 to 2025, combining ERA5-Land reanalysis with MODIS satellite observations for a comprehensive thermal picture.
ERA5-Land provides continuous daily coverage at ~9km resolution (air temperature at 2m and soil temperature). MODIS MOD11A2 provides 8-day composite land surface temperature from satellite at 1km resolution, with gaps from cloud cover.
More from Biosphere
Monthly Temperature (Last 5 Years)
Mean temperature with max/min range shaded. ERA5-Land 2m air temperature.
MODIS Satellite LST vs ERA5 Air Temperature
Comparing satellite-measured land surface temperature (MODIS, teal) with modelled air temperature (ERA5, orange). MODIS is typically warmer in summer due to direct surface heating.
Annual Mean Temperature Trend
Annual mean air temperature, 2000–2025. Dashed line shows the linear warming trend.
Frost Days Per Year
Number of days per year where minimum temperature fell below 0°C. Declining frost days indicate warming winters.
Growing Degree Days (Base 5.5°C)
Annual accumulated warmth above 5.5°C — a key agricultural metric. Higher GDD means a longer, warmer growing season for crops and vegetation.
Methodology & Data Sources
ERA5-Land (Open-Meteo) provides continuous daily temperature records at ~9km resolution. It is a reanalysis product — a model-based reconstruction that assimilates observations to fill gaps. Variables include 2m air temperature (max, min, mean) and 0–7cm soil temperature. ERA5-Land is excellent for trend analysis because it has no missing days.
MODIS MOD11A2 measures actual land surface temperature from the Terra satellite at 1km resolution, composited every 8 days. LST is the radiative skin temperature of the ground — it can differ significantly from air temperature, especially in summer (bare soil heats up more than air) and winter (snow-covered ground stays colder). Cloud cover causes data gaps, particularly in winter months when the IoM is frequently overcast.
Why do they differ? ERA5 measures air temperature at 2m above ground; MODIS measures the radiative temperature of the land surface itself. In summer, MODIS LST is typically 2–5°C warmer than ERA5 air temperature. In winter, the difference is smaller. The comparison helps validate both datasets and reveals the urban/rural heat signal.
Muñoz Sabater, J., (2019): ERA5-Land hourly data from 1950 to present. Copernicus Climate Change Service (C3S) Climate Data Store (CDS). | Wan, Z., Hook, S., Hulley, G. (2021). MODIS/Terra LST/E 8-Day L3 Global 1km SIN Grid V061. | Generated 25/03/2026.
Decade-by-Decade Trends
| Decade | Mean Temp | Avg Frost Days/yr | Trend |
|---|---|---|---|
| 2000s | 8.0°C | 7 | +0.2°C/decade |
| 2010s | 7.7°C | 20 | +0.3°C/decade |
| 2020s | 7.9°C | 37 | +2.1°C/decade |
Warming trend
The Isle of Man, like much of the British Isles, shows a clear warming trend since 2000. Mean temperatures have risen, frost days have declined, and growing seasons have lengthened. This has implications for agriculture, biodiversity, and energy use.
Frost & growing season
Declining frost days mean a longer frost-free growing season. Growing Degree Days (GDD) track accumulated warmth above 5.5°C — more GDD means more energy available for crop and plant growth. Higher GDD can also increase pest and disease pressure.
Satellite vs model
MODIS measures the land surface directly from space — actual ground temperature, not air temperature. ERA5-Land reconstructs conditions from a weather model. Comparing both gives confidence in temperature trends and reveals surface heating patterns.