What is the drought code?

A 0–100 rolling estimate of deep-fuel moisture deficit, integrating precipitation shortfall, evapotranspiration, and temperature over roughly the prior 60–90 days. A DC over 70 with elevated heat-day counts is the classic pre-red-flag posture.

How does drought code affect canopy vigor?

Sustained high DC drives crown dieback in stressed species (black spruce, balsam fir, coastal redwood at range edges). Canopy vigor lags DC by roughly a season, which makes DC a useful early-warning signal for stand health, not just fire risk.

When should I act on drought code?

DC > 55: monitor and pre-position. DC > 70: restrict ignition sources on your permit, cancel high-heat operations. DC > 85 with any heat-day streak: red-flag posture regardless of FWI.

Drought code for forestry: the leading indicator explained.

Drought code, explained.

Surface fuels dry in hours. Deep fuels dry over weeks. Drought code tracks the deep layer — which is what actually decides whether a spot ignition holds.

How it's built

Drought code integrates precipitation shortfall, potential evapotranspiration, and daily temperature over the prior 60–90 days into a 0–100 score. It's slow to move up and slow to move down, which is exactly the property that makes it useful for planning.

Operational thresholds

DC < 40: baseline. Routine operations.
DC 40–55: watch. Increase weather-check cadence.
DC 55–70: pre-position. Restrict high-heat activity on hot afternoons.
DC > 70: restricted operations. Cancel ignition-risk work on ridgelines.
DC > 85: red-flag posture regardless of the daily FWI.

Track it on your units

The Forest Health workspace renders drought code as a 20-year trajectory per unit with your today value scrubbable. Explore the pattern in the forestry demo.

Common questions

What is the drought code?: A 0–100 rolling estimate of deep-fuel moisture deficit, integrating precipitation shortfall, evapotranspiration, and temperature over roughly the prior 60–90 days. A DC over 70 with elevated heat-day counts is the classic pre-red-flag posture.
Why is it a leading indicator?: Surface fuels dry in hours. Deep fuels — duff, downed logs, coarse woody debris — dry over weeks. Drought code tracks the deep layer, which is what determines whether a spot ignition holds long enough to become a fire.
How does drought code affect canopy vigor?: Sustained high DC drives crown dieback in stressed species (black spruce, balsam fir, coastal redwood at range edges). Canopy vigor lags DC by roughly a season, which makes DC a useful early-warning signal for stand health, not just fire risk.
When should I act on drought code?: DC > 55: monitor and pre-position. DC > 70: restrict ignition sources on your permit, cancel high-heat operations. DC > 85 with any heat-day streak: red-flag posture regardless of FWI.

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