Home  ›  Signals  ›  LH NC Heat Stress

· Analytic

LH NC Heat Stress

North Carolina is the third-largest US hog state. When summer heat and coastal humidity stack up, pigs stop gaining weight. We still count the severe-heat days in the hog belt — but the forward edge against a clean tradable benchmark is too small to size on.

At a glance

As of Oct 29, 2026. Updated nightly.

OBJECTIVE

North Carolina produces close to ten million market hogs a year, almost all of them concentrated in the Eastern coastal plain where Smithfield Foods and Tyson have built out dense finishing operations. It is a brutal environment for pigs in summer. Coastal humidity does not let the heat dissipate overnight, and when daytime temperatures push into the nineties the combined heat-humidity load on the animals is severe enough to measurably hurt production.

Hog producers measure this with the Temperature-Humidity Index (THI). When THI pushes above 90 — think a 98-degree afternoon with 70 percent humidity, or a 95-degree afternoon with saturating 85 percent coastal humidity — pigs are in the emergency-stress range where feed intake collapses and mortality risk rises. (Finishing efficiency actually starts dropping much lower, around THI 84, but THI 90+ is where acute events happen.) Enough severe-THI days in a row and you get measurably less pork coming out of that region a few months later, through PRRS and PEDv disease pressure and feed-intake collapse.

This signal counts the number of severe-THI days (THI greater than 90 at the day peak) over the last 30 days in the North Carolina hog belt, standardizes that count against the historical distribution, and bounds the result between -1 and +1. Positive readings mean many severe heat days recently; negative readings mean mild conditions. The signal is seasonal by physical design — it is near zero outside June through September because the physical driver (sustained Carolina coastal heat) is not present in winter.

A note on status: this signal was removed from the LH Supply Census Composite on 2026-10-30 after re-benchmarking against the proper CSI tradable Lean Hogs back-adjusted series. The information coefficient against the clean tradable benchmark came in at +0.009 with a p-value of 0.37 — statistically indistinguishable from zero. Historical regime bands against the tradable benchmark show the Sustained Heat band (37.1% of days) delivering only +0.47 percent average forward 60-day return versus the baseline of +0.43 percent mean, -0.22 percent median; the Normal band delivers -0.86 percent; Mild Conditions delivers -0.41 percent. None of these separates far enough from baseline to earn a seat in a sized composite. The page stays live for research-interest readers who want to track the physical mechanism, but it is informational only — it no longer contributes to any sized directional call on Lean Hogs. See the methodology section for the full re-benchmarking story.

LIVE CHART

THE TAKEAWAY

THE REGIME MAP

Three bands sit on this signal, measured against the CME Lean Hogs back-adjusted tradable return — the proper price series a real futures trader would experience. Sustained Heat (37.1% of trading days) delivers an average fwd60d of +0.47% — essentially matching the baseline of +0.43% mean (median -0.22%). Normal (9.0% of days, today’s band) delivers -0.86%. Mild Conditions (53.9% of days) delivers -0.41%. None of these bands separates meaningfully from baseline, and the overall information coefficient of +0.009 with p-value 0.37 is statistically indistinguishable from zero. This is why the signal was removed from the LH Supply Census Composite on 2026-10-30. The physical mechanism continues to operate on hogs in NC coastal plain finishing yards every summer, but at the 60-day forward horizon on tradable Lean Hogs returns, no edge survives.

Thresholds are tuned on the historical distribution of 30-day severe-THI counts in the NC hog belt. "Severe" means THI greater than 90 at the day’s peak, which is the swine-industry standard for measurable production stress. Band breakpoints are expressed in standard-deviation units of the raw count.

THE TRACK RECORD

Scroll inside the table for the full history. Forward 60-day LH 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.

We watch one physical quantity: how many severe-heat days have hit the North Carolina hog belt in the last 30 days. “Severe” means the Temperature-Humidity Index (THI) crossed 90 at the day’s peak, which is the swine-industry’s own standard threshold for stress that measurably affects pig performance. We tally those days over a rolling 30-day window, then z-score the count against the historical distribution so we know what counts as a big number for this specific stress metric. The intuition the mechanism makes: a cluster of severe-THI days in June, July, or August should mean pigs in that region are not finishing as efficiently as normal, which should mean slightly less pork coming to packing plants two to four months later, which should mean a tighter US pork market and a tailwind for Lean Hogs futures. That is the theory. In practice, as the next sections will discuss, the data does not line up with the theory as cleanly as we would like, which is why this signal is sized conservatively.

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 Oct 30, 2026 10:50 AM ET