· Analytic
Z4426 Corn Belt Storm Hail Activity
The 30-day rolling count of NOAA-reported hail events across eight Corn Belt states, z-scored on 1,260-day rolling window. The empirical state-to-corn-forward-return direction is OPPOSITE the naive "hail = crop damage = bull corn" reading: HIGH hail historically PRECEDES bearish corn forward returns.
Current reading
-0.732
Moderate Neg
DAILY · SIGNAL
As of Oct 30, 2026. Updated nightly.
Current composite
-0.7219
On the plus-or-minus one scale; hail activity across belt is quiet
Signal state
Moderate NEG
69 days in episode
All-time percentile
4.7th
Bottom 5 percent of 36 years
EXTREME_POS corn fwd 60d
-3.39%
2,299 days (25.6%), HAC t -3.92 sig at 1%
EXTREME_NEG corn fwd 60d
+1.39%
3,907 days (43.5%), HAC t +2.74 sig at 1%
Current contribution to ML Auto Corn Composite V9
+0.058
8.0 percent weight × -1 polarity × -0.722 value
OBJECTIVE
The NOAA Storm Events Database records every severe-weather event reported to the National Weather Service across the United States back into the 1950s. Hail events specifically , distinct from thunderstorms, tornadoes, and wind damage , are recorded by location and date with hail-stone size estimates. This signal counts hail events per day across the eight-state Corn Belt (Iowa, Illinois, Indiana, Nebraska, Ohio, Missouri, South Dakota, Minnesota , collectively approximately 80 percent of US corn production), applies a 30-day rolling sum to smooth the point-event-based data into a continuous activity signal, and z-scores on a 1,260-day (5-year) rolling window. Positive signal values mean elevated hail activity across the belt; negative values mean quiet. The naive reader-expectation is that hail causes direct crop damage and should be bullish for corn forward returns. The 36-year empirical pattern across 8,979 trading days runs OPPOSITE this intuition. EXTREME_POS state (val above plus 0.5, high hail activity) delivers mean corn fwd 60d of minus 3.39 percent (HAC Newey-West t minus 3.92, significant at the 1 percent level, 2,299 state-days, edge minus 2.91 pp below the minus 0.48 percent baseline). EXTREME_NEG state (val below minus 0.5, quiet hail) delivers plus 1.39 percent (HAC t plus 2.74, significant at 1 percent, 3,907 state-days). Both tails highly significant and in the OPPOSITE direction from the naive thesis. The economic interpretation: hail reports are DOWNSTREAM of the same convective-storm regime that delivers favorable late-summer moisture to the Corn Belt. High hail activity signals an active storm regime WITH moisture, generally favorable for corn yield, hence bearish forward returns. Low hail signals a quiet, dry regime that reduces late-summer moisture and stresses crop, hence bullish forward returns. ML Auto Corn Composite V9 wires the signal at polarity sign minus one to translate the empirical direction into a trend-following contribution to the composite. Today the signal reads minus 0.7219, in EXTREME_NEG territory for 69 consecutive trading days at the 4.7 percentile of 36 years , a quiet-hail regime. Historical pattern delivers plus 1.39 percent corn fwd 60d (via polarity flip, this contributes positively to ML Auto Corn Composite V9: +0.058, one of today’s positive contributions). Read on for the mechanism, the signature historical cases, and the current reading in context.
LIVE CHART
Thirty-six years of NOAA Storm Events hail activity across 8 Corn Belt states.
COMPOSITE
-0.7 / 100
STATE
Moderate Neg
PHASE
-1
FWD 60d
+4.64% (baseline +2.31%)
SAMPLE N
9,039 days
TODAY’S PLAYBOOK READING
STATE
Moderate Neg
STATE AND PERCENTILE
EXTREME_NEG at the 4.7 percentile , bottom-5-percent of 36 years. Quiet severe-weather regime.
WHY THE SIGNAL IS HERE
Fall post-harvest windows (October-November) tend to have lower severe-weather frequency; combined with the 2026 dry-regime signal, hail counts are deeply below the 5-year rolling norm.
POSTURE FOR THE WEEKS AHEAD
EXTREME_NEG delivers plus 1.39 percent corn fwd 60d (HAC t plus 2.74 sig at 1 percent). The quiet-hail regime is empirically bullish for corn forward returns.
WHAT THE CHART SHOWS
The composite sits at -0.73 in the Hail Activity Low band. The 30-day rolling count of NOAA-reported hail events across the eight Corn Belt states is well below the 5-year rolling baseline. Per the contrarian interpretation, this is a dry-regime signature. CBOT front-month corn (orange, right axis) sits near $4.48/bu.
TOP INPUTS FIRING
- Primary composite -0.73 State Hail Activity Low, moderate-neg band. 30-day rolling hail-event count z-scored well below baseline.
- NOAA storm reports, 8 Corn Belt states, 30-day rolling Daily hail event counts from NOAA Storm Prediction Center reports across Iowa, Illinois, Indiana, Nebraska, Minnesota, South Dakota, Ohio, Missouri. 30-day rolling sum, z-scored on 1,260-day window.
- IC vs CBOT corn fwd 60d: Spearman -0.155, p=2.9e-49 (CONTRARIAN) Deeply significant NEGATIVE IC. The contrarian interpretation reads elevated hail as a wet-regime signature (bearish corn), not crop-damage bullish.
THE TAKEAWAY
What this means for you today
THE CONTRARIAN DIRECTION IS EMPIRICAL FACT
The naive reading of hail activity is: hail destroys crops, so high hail activity should be bullish for corn. The 36-year state-conditional empirical direction runs OPPOSITE this: high hail activity (EXTREME_POS) has historically PRECEDED minus 3.39 percent corn fwd 60d (HAC t minus 3.92 sig at 1 percent). The explanation: hail reports are DOWNSTREAM of the same convective-storm regime that delivers favorable late-summer moisture to the Corn Belt. An active hail-reporting regime signals an active-storm, moisture-abundant regime that is bull for corn YIELD → bear for forward prices (prices already decline as the market anticipates the strong yield). A quiet hail regime signals a dry, stressed-crop regime → bull forward prices.
THE ML Auto Corn Composite V9 POLARITY FLIP ALIGNS WITH EMPIRICAL DIRECTION
ML Auto Corn Composite V9 wires the signal at polarity sign minus one. The polarity flip translates the empirically-correct direction (high hail = bearish-for-corn-forward) into a bearish ML Auto Corn Composite V9 contribution. The current reading minus 0.7219 (quiet hail) with polarity minus one yields a POSITIVE ML Auto Corn Composite V9 contribution of plus 0.058 , the LightGBM composite correctly captures that quiet hail = bullish-for-corn regime.
THE HONEST CAVEAT
The signal reads EVENT-COUNT data, which is inherently reporting-biased: a hail event that caused no damage near populated areas may not be reported, while a hail event in a corn field may be well-documented. The signal captures REPORTED hail, not necessarily agronomically-impactful hail. However, over 36 years of history the reporting bias is approximately stable, so year-over-year signal values are directionally meaningful. The 2026-10-25 persona code review did not flag publication-lag issues; NOAA Storm Events reports typically land within 7-14 days of event dates.
THE REGIME MAP
The three Corn Belt storm-hail activity regime states, forward returns and sample share
Behavior across the 30-day rolling count of NOAA-reported hail events across eight Corn Belt states, z-scored on 1,260-day (5-year) rolling window. CONTRARIAN interpretation: high hail = active severe-weather / wet-regime signature (bearish corn via comfortable-moisture setup), NOT crop damage bullish.
| State | Phase | Share | Fwd 60d | HAC t | Edge vs baseline | Last firings |
|---|---|---|---|---|---|---|
| Hail Activity Low TODAY | – | 52.5% (4751 d) | +0.38% | +0.09pp | Aug 2026, Aug 2025, Sep 2024 | |
| Hail Activity Neutral | 0 | 15.6% (1412 d) | -0.25% | -0.54pp | Jul 2026, Jun 2026, Jun 2026 | |
| Hail Activity High | + | 31.9% (2881 d) | -1.59% | -1.88pp | Jun 2026, Jun 2026, Jun 2026 |
The historical pattern
Methodology
THE TRACK RECORD
State changes
| State | Start | End | Duration | Fwd 60d SPY |
|---|---|---|---|---|
| Extreme Pos | 10/23/2024 | 03/13/2025 | 97d | +4.92% |
| Normal | 03/14/2025 | 03/28/2025 | 11d | +7.16% |
| Extreme Neg | 03/31/2025 | 06/16/2025 | 54d | +9.38% |
| Normal | 06/17/2025 | 07/09/2025 | 15d | +10.02% |
| Extreme Neg | 07/10/2025 | 07/11/2025 | 2d | +6.93% |
| Normal | 07/14/2025 | 08/26/2025 | 32d | +7.09% |
| Extreme Pos | 08/27/2025 | 03/09/2026 | 133d | +0.91% |
| Normal | 03/10/2026 | 03/25/2026 | 12d | +11.80% |
| Extreme Neg | 03/26/2026 | 04/08/2026 | 9d | +13.72% |
| Normal | 04/09/2026 | 04/10/2026 | 2d | +9.97% |
| Extreme Neg | 04/13/2026 | 05/27/2026 | 32d | +9.56% |
| Normal | 05/28/2026 | 05/29/2026 | 2d | +1.18% |
| Extreme Neg | 06/01/2026 | 06/02/2026 | 2d | +0.99% |
| Normal | 06/03/2026 | 06/03/2026 | 1d | +2.00% |
| Extreme Neg | 06/04/2026 | 06/15/2026 | 8d | +1.32% |
| Normal | 06/16/2026 | 06/18/2026 | 3d | +1.86% |
| Extreme Neg | 06/22/2026 | 07/09/2026 | 13d | +1.30% |
| Normal | 07/10/2026 | 07/17/2026 | 6d | +2.63% |
| Extreme Pos | 07/20/2026 | 10/23/2026 | 69d | +4.84% |
Scroll inside the table for the full history. Forward 60-day SPY is measured from each run’s start date; a reader cannot trade off a start-date they only identify in hindsight, so this is a transparency log, not an alpha claim. Asterisked (*) returns are partial. The run is less than 60 trading days old. The full 60-day comparable fills in as more data arrives.
What this measures
The engine queries NOAA_STORM_EVENTS from `weather_data.NOAA_STORM_EVENTS` for `event_type=’Hail’` in eight Corn Belt states. Counts events per day. Reindexes to daily with fill-value 0. Applies 30-day trailing rolling sum to convert point-event data to continuous activity series. Z-scores on 1,260-day rolling window with 60-day minimum. Tanh-bounds. Five-state machine on the final the primary composite.
GO DEEPER
Want the full depth?
The full research brief adds methodology detail on the NOAA Storm Prediction Center data, the eight-state Corn Belt coverage, and why the contrarian interpretation (hail = wet regime signature) reads opposite the naive crop-damage framing. Includes historical case studies anchored to actual severe-weather regimes, the three-regime state-conditional table, and the methodology for pairing with Silking Pace, Condition WoW, Nino 3.4, and the Corn Cycle DNA playbook.
Taxonomy, polarity, state labels
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 02, 2026 01:08 PM ET