Crop health, water balance and soil moisture

Open-Meteo ERA5 and NASA POWER data · 16 global grain zones

Last update: 3 October 2026

Reference climatology

27/08/2026

37 days ago

30-year normal · annual refresh

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How to read this chart

Water Balance (WB)

Each day: rainfall received minus water evaporated by the soil. Over 30 days, if the total is negative, the crop lacks water. Positive, it holds on.

WB -40mm over 30 days: the soil loses 40mm more than it receives. At this stage, you can see it in the leaves.
Score 0 to 100

60% water balance + 40% soil moisture, reduced to a single number. 75+, the crop is comfortable. Below 40, it needs watching.

How to read the score: 60% water balance in absolute terms (−100 mm over 30 days → 0, +100 mm → 100) and 40% soil-moisture deviation from its climatic normal. The normal is computed over 2001-2020 from Open-Meteo ERA5, the same source as the measurements themselves, with means and standard deviations actually observed. The water-balance anomaly shown next to the millimetres compares the current total against the monthly normal: that is what separates a dry month from an abnormally dry one.

75+ Excellent60 Good45 Average30 DegradedCritical
Alerts

An alert triggers in two cases:

Deficit : WB over the last 14 days below -30mm. Roots start to suffer, yield follows.
Excess : WB over the last 14 days above +30 mm. The soil stays waterlogged, roots lack air, fungi proliferate, and machinery cannot enter the field.
Abbreviations glossary
WBWater Balance = precipitation − evapotranspiration (mm/day)
WB 30d30-day cumulative WB, showing the underlying trend
WB 14d14-day cumulative WB (deficit alert if < -30mm)
ET0Reference evapotranspiration (FAO Penman-Monteith): what the soil evaporates in fair weather without water stress
WB sc.Water Balance Score (0-100), calculated on 30-day WB. 0 = severe deficit, 50 = balanced, 100 = maximum surplus
Soil sc.Soil Moisture Score (0-100): compares current moisture to the climatological normal measured on Open-Meteo ERA5, 2001-2020 window. 50 = within normal range
ScoreFinal health score = 60% WB sc. + 40% Soil sc. A single number summarising crop condition
Soil m.Volumetric soil water content in the root zone (28-100cm), in m³/m³: the volume of water held in a volume of soil. It is not a fill level, 0.24 m³/m³ does not mean “soil 24% full”
Forecast WB 5dWater balance accumulated over the next 5 days, computed from the weather forecast, not from the observed archive. It feeds neither the score nor the alerts, and describes a nearby point, a few kilometres from the archive point.

Sources: Open-Meteo ERA5 (archive) · Open-Meteo Forecast · NASA POWER (30-year climatology) · Daily update 7h UTC