Claim check: The natural gas winter rally
“Natural gas rallies into winter: buy in autumn, sell in winter.”
What the data says
Does not hold Not supported by the data: September to December returned -3.7% a month on average against -0.4% for the other months in natural gas (n = 66 months, 2010-01-04 to 2026-11-10; t = -1.6, likely noise). We see no sign of the claimed effect.
No effect we can tell from chance, or the opposite effect.
Who says it
Energy traders and commodity seasonality guides.
Origins are as commonly cited and were not independently verified.
How we tested it
Monthly returns of the natural gas ETF UNG. The trade buys at the end of August and sells at the end of December, so it earns the September to December monthly returns; these are compared with the other eight months (Welch t-stat). UNG holds futures and loses value as contracts are rolled, which affects every month.
Results
| Market | Observations | Mean | Rest | Difference | Up share | t-stat | Rank of 12 | Reading |
|---|---|---|---|---|---|---|---|---|
| Natural gas | 66 | -3.7% | -0.4% | -3.28% | 36% | -1.6 (likely noise) | — | No effect |
Average monthly return by calendar month (Natural gas)
Stability across the two halves of history
A saying that only works in one half of the history is not much of a rule. Each row shows the effect in the full history, the first half and the second half; green means the claimed effect was present.
| Market | Full history | First half | Second half |
|---|---|---|---|
| Natural gas | -3.3% | -2.0% (32) | -4.4% (34) |
The honest caveat
UNG has heavy roll-decay and structural losses; seasonality is overshadowed by contango.
Descriptive statistics from historical data, before costs. Not a forecast and not investment advice.
Questions
Natural gas rallies into winter: buy in autumn, sell in winter.
Not supported by the data: September to December returned -3.7% a month on average against -0.4% for the other months in natural gas (n = 66 months, 2010-01-04 to 2026-11-10; t = -1.6, likely noise). We see no sign of the claimed effect.
How was this claim tested?
Monthly returns of the natural gas ETF UNG. The trade buys at the end of August and sells at the end of December, so it earns the September to December monthly returns; these are compared with the other eight months (Welch t-stat). UNG holds futures and loses value as contracts are rolled, which affects every month.