KC SPECIALIST · Softs / Disease Risk
Z102411 – [KC] Central America Roya CHIRPS Wet Anomaly Signal
Central American coffee-belt wet-weather anomalies elevate roya leaf-rust risk and historically precede Arabica supply shocks that drive forward 60-day returns.
At a glance
POST-SEASON SIGNATURE
Current reading
-0.001
SEASONAL STATE
POST-SEASON SIGNATURE
Post-wet-season residual roya pressure extends into early dry season before infection…
Signal state
On Trend
25 days in Neutral phase
Updated
Nov 04, 2026
CHIRPS daily release
Sample
36-year window
Daily cadence; 1990 onward
As of Nov 04, 2026. Updated nightly. · NEXT WINDOW APR-OCT CENTRAL AMERICA WET SEASON
SIGNAL OVERVIEW
Hemileia vastatrix (coffee leaf rust, known regionally as roya) is the most destructive disease of Arabica coffee. The 2012-2013 Central American roya outbreak destroyed roughly 20 percent of the regional harvest and contributed to a KC price rally of roughly 73 percent. Wet-weather anomalies in the Colombia, Honduras, and Guatemala coffee belts are the primary leading indicator for roya pressure because prolonged leaf wetness is the key epidemiological trigger. The signal reads rolling 90-day CHIRPS precipitation across the three coffee belts, computes a 5-year z-score, averages, and tanh-bounds. Daily Spearman IC against Arabica forward 60-day returns is plus 0.099 at p-value 5.2e-21 across 8,947 observations, strongly significant on the 36-year sample. Phase plus 1 firings (wet anomaly, roya risk elevated) deliver plus 0.52 pp above the plus 2.32 percent baseline. Phase minus 1 firings deliver minus 1.30 pp. 1.82 pp directional spread. The signal is a slow-lead disease-risk overlay not a short-horizon trigger.
LIVE CHART
KC Central America Roya CHIRPS Wet Anomaly Signal
What the chart is showing right now. The dark line is the rolling 90-day CHIRPS precipitation averaged across Colombia, Honduras, and Guatemala coffee-belt grid cells, z-scored on a 5-year rolling window and tanh-bounded. Positive composite means wet anomaly (elevated roya leaf-rust risk); negative composite means dry anomaly (reduced disease pressure). The bronze line in the middle panel is ICE US Coffee C first-nearby. The bottom panel tracks the trailing 252-day Spearman information coefficient between the composite and Arabica forward 60-day returns.
COMPOSITE
-0.001 / tanh
STATE
On Trend
PHASE
-0.00
PHASE +1 EDGE
+0.52 pp
PHASE -1 EDGE
-1.30 pp
TODAY’S PLAYBOOK READING
STATE
NEUTRAL
STATE AND HISTORY
On Trend firing at composite -0.001, 25 trading days running in Neutral phase. Phase +1 (Roya Risk Elevated) delivers plus 2.84 percent fwd60d / plus 0.52 pp above plus 2.32 percent baseline. Phase -1 (Dry Anomaly) delivers plus 1.02 percent / minus 1.30 pp below baseline. Daily Spearman IC plus 0.099 at p-value 5.2e-21 strongly significant.
THE DISEASE-RISK MECHANISM
Hemileia vastatrix (coffee leaf rust, roya) is the most destructive disease of Arabica coffee. Prolonged leaf wetness during the Central American wet season is the key epidemiological trigger for roya outbreaks. When precipitation runs well above the 5-year norm across Colombia, Honduras, and Guatemala coffee belts, roya pressure elevates and Arabica supply shocks follow 60-90 days later.
HOW TO POSITION
Directional disease-risk overlay for Arabica. Roya Risk Elevated firings flag bullish supply- shock setups with Arabica strength following at 60-day horizon. Dry Anomaly firings flag bearish low-disease regimes. Pair with CHIRPS Brazil rainfall, ENSO dipole, and USDA PSD Colombia- Honduras-Guatemala production for stacked disease-plus-supply conviction.
WHAT THE CHART SHOWS
The composite sits at -0.001 in the On Trend band. Central American coffee-belt precipitation has run near the 5-year z-score mean through 2026 consistent with neutral roya disease-risk regime.
TOP INPUTS FIRING
- Primary composite -0.001 State On Trend, 25 days running in Neutral phase.
- Central American CHIRPS 90-day near 5-year norm Raw z-score -0.00; precipitation across Colombia, Honduras, and Guatemala coffee belts has run near the 5-year rolling norm through 2026.
- Daily IC strongly significant, non-overlap borderline Daily Spearman IC plus 0.099 at p-value 5.2e-21 strongly significant on full distribution. Non-overlap IC plus 0.124 at p-value 0.13 borderline significant on 150 samples.
THE TAKEAWAY
What this means for you today
THE DISEASE CALL
Composite -0.001, On Trend. Central American coffee-belt precipitation has run near the 5-year z-score mean through 2026 consistent with neutral roya disease-risk regime. Signal in On Trend bucket for 25 days; forward 60-day edge in Phase 0 historically runs plus 0.81 pp above baseline.
THE EMPIRICAL CONTEXT
Daily IC plus 0.099 at p-value 5.2e-21 strongly significant on 36-year sample. Phase +1 (Roya Risk Elevated) delivers plus 0.52 pp above baseline; Phase -1 (Dry Anomaly) delivers minus 1.30 pp. 1.82 pp directional spread with slow-lead disease-risk pattern.
THE HONEST CAVEAT
Non-overlap IC at 60-day sampling plus 0.124 at p-value 0.13 borderline significant on 150 samples. The signal is a slow-lead disease-risk overlay; roya outbreaks take weeks-to-months to develop from the initial wet-anomaly trigger. Treat as supply-shock setup lens not a short-horizon trigger.
THE REGIME MAP
The three phases, forward returns and sample share
Computed from 8,947 post-warmup trading days (1990 onward). Baseline Arabica fwd60d mean plus 2.32 percent. Phase +1 (Roya Risk Elevated) delivers +0.52 pp edge; Phase -1 (Dry Anomaly) delivers -1.30 pp. 1.82 pp directional spread with daily IC plus 0.099 strongly significant.
| State | Phase | Share | Fwd 60d | HAC t | Edge vs baseline | Last firings |
|---|---|---|---|---|---|---|
| Roya Risk Elevated | +1 | 25.0% (2241 d) | +2.84% | +0.52pp | 2012-13, 2010, 1998 | |
| On Trend TODAY | 0 | 39.2% (3508 d) | +3.12% | +0.81pp | 2026 (current) | |
| Dry Anomaly | -1 | 27.9% (2500 d) | +1.02% | -1.30pp | 2018-19, 2015 |
The historical pattern
Signature episodes in the 36-year sample
What this measures
Z-score of rolling 90-day CHIRPS precipitation across Colombia, Honduras, and Guatemala coffee-belt grid cells on a 5-year rolling window, averaged, tanh-bounded. Positive composite equals wet anomaly (roya leaf-rust risk elevated); negative composite equals dry anomaly (reduced disease pressure). Target ICE US Coffee C first-nearby back-adjusted close.
Why it matters
Why Central American roya disease matters
Hemileia vastatrix (coffee leaf rust, roya) is the most destructive disease of Arabica coffee and the 2012-2013 Central American outbreak remains the canonical historical anchor with roughly 20 percent regional harvest loss and a KC price rally of roughly 73 percent. Prolonged leaf wetness during the April-October wet season is the key epidemiological trigger; wet-anomaly precipitation across Colombia, Honduras, and Guatemala coffee belts is the primary leading indicator for disease pressure 60-90 days forward.
How to use this signal today
Directional disease-risk overlay for Arabica positioning. Roya Risk Elevated firings flag bullish supply-shock setups where Arabica strength historically follows at 60-day horizon; Dry Anomaly firings flag bearish low-disease regimes. Pair with CHIRPS Brazil rainfall (different coffee region), ENSO dipole (weather driver), and USDA PSD Colombia-Honduras-Guatemala production for stacked disease- plus-supply conviction.
Risk overlay
Daily IC strongly significant but non-overlap test (150 independent 60-day samples) plus 0.124 at p-value 0.13 borderline significant. Roya outbreaks require weeks-to-months to develop from initial wet-anomaly triggers; the signal is a slow-lead supply-shock setup lens not a short-horizon trigger. Treat as directional disease overlay for 60-90 day positioning horizons.
Signal consumers and siblings
Not investment advice · The analysis on this page is informational and educational. Signal readings, historical case figures, and empirical statistics are derived from publicly available data and are provided without warranty. Hypothetical performance results have inherent limitations, including the benefit of hindsight. Readers who intend to trade should consult a licensed investment professional and see the research brief for the full disclaimer.
Last refreshed Nov 06, 2026 12:35 AM ET