When is heating oil cheapest?
What the ten years actually show
The seasonal effect is small next to the year-to-year swing. On average October ran 7% above its year's mean and was above it in 7 of the 10 years; November ran 5% above; April ran 5% below and was under it in 7 of 10. Every other month sits within 3% of the average. Meanwhile the cheapest month of the year landed in 7 different months across the decade (January three times, May twice), so no calendar month is a reliable low.EIA
Why wholesale and not the delivered price: EIA's residential survey runs October to March and in most years publishes nothing from May to September, so a twelve-month delivered-price pattern cannot be built from it. The delivered price follows the wholesale price with a dealer margin on top; see wholesale vs retail.
What that means for a summer pre-buy
Locking a price in summer avoids the October run-up in the years it happens, but on this record summer was not a dependable discount: July and August sat right at the yearly average. The case for a pre-buy rests on how much you value a fixed bill against the risk that prices fall after you lock, not on a seasonal low. Run the break-even.
Dates worth watching
NOAA's Climate Prediction Center issues its winter outlook in mid-October, and EIA's Winter Fuels Outlook publishes with the October Short-Term Energy Outlook. Both shape expectations going into the season.NOAA