Off-season buyingEIA monthly residentialWeek of 30 March 2026

Summer Propane Price Per Gallon: The Off-Season Buying Window

The cheapest weeks of the year to buy residential propane are almost always in August and September. This page covers why, by how much, and how a homeowner captures the summer discount.

5-year summer trough vs winter peak

14%summer discount, 5-yr avg

5-yr avg summer low: $2.388 per gallon; 5-yr avg winter high: $2.765. 7 of the last 12 years saw the annual low in August or September.

Why summer is the residential low

Three factors drive the August-September trough in residential propane prices. First, heating demand is effectively zero from May through September across most of the US. The exception is a small share of households using propane for water heating year-round (a 50-gallon propane water heater might use 200 to 300 gallons per year regardless of season), but the volumes are small relative to winter heating demand. Without heating draw, the residential delivery channel goes very quiet for four to five months.

Second, US propane production runs essentially flat year- round (gas processing plants continue to extract propane from the wet natural gas stream regardless of season), which means inventory rebuilds aggressively through spring and summer. EIA Weekly Petroleum Status Report data shows US propane inventory typically rises from late-March seasonal lows of 30 to 50 million barrels to late-September peaks of 80 to 100 million barrels. The rebuilding inventory caps wholesale price floor: with storage caverns filling, Mont Belvieu spot has limited upward pressure through the summer months.

Third, US LPG exports run more steadily through summer (Asian and European propane demand is less seasonal than US demand), which provides a steady demand sink without driving prices up. Net of all three factors, summer Mont Belvieu spot typically runs 30 to 50% below the winter peak, and the residential survey follows with the typical lag.

What the EIA off-season figures show

The EIA Weekly Heating Oil and Propane Survey is a winter- season-only weekly series (October through March). For the off-season, EIA publishes a monthly residential propane figure (series M_EPLLPA_PRS_NUS_DPG). The monthly archive back to the early 1990s makes the seasonal pattern unmistakable: virtually every year shows the annual residential low in August or September, with a few years where the low slips to early October or late July.

Looking at the 5-year history at the bottom of our seasonal patterns page: the annual low month was August or September in 7 of the last 12 years tracked. The years where the low slipped earlier or later were typically driven by unusual events (2014 saw a delayed low because the polar vortex had drained inventory into spring; 2020 saw flat prices through summer because of pandemic demand drop). The off-season monthly average typically runs 18 to 32% below the winter monthly peak for the same calendar year.

How to capture the summer discount

Three mechanisms let homeowners buy at the summer low rather than the winter average or peak.

Summer fill program

The most common propane dealer offering is a summer-fill program: the dealer agrees to deliver the customer's tank capacity at the summer per-gallon price, typically between June and September, with the customer paying on delivery at the summer rate. The discount versus the dealer's standard winter price typically runs 15 to 30 cents per gallon, sometimes more. The catch: the customer needs a tank large enough to hold most or all of the annual consumption. A 500-gallon tank for a 700-gallon-per-year household captures most of the discount; a 250-gallon tank for a 1,200-gallon-per-year household captures only a fraction.

Pre-buy program

Similar to summer fill but with payment up front: the customer pays for the season's expected gallons at the pre-buy price in June or July, and the dealer delivers as needed through the heating season. The pre-buy price typically reflects the dealer's actual rack purchase forward-bought against the summer Mont Belvieu floor, often locking in a per-gallon price 10 to 25 cents below what the dealer will charge will-call customers in January. The customer carries the cost-of-capital risk (your money tied up in propane for six months) but locks the price.

Cap contracts

A cap contract lets the customer pay the will-call market price through the season but with a ceiling that the dealer absorbs if exceeded. The cap typically costs 10 to 25 cents per gallon over the pre-buy equivalent, paid as an up-front fee or built into the per-gallon rate. Useful for homeowners who want to participate in downward price moves while preserving budget certainty against the polar vortex scenario.

The cost-of-capital math for pre-buy

Pre-buy programs are sometimes derided as "free loans to the propane dealer". The math is more nuanced. Suppose a homeowner pre-buys 800 gallons in July at $1.80 per gallon ($1,440 paid up front) versus paying will-call through the season at an average of $2.10 per gallon ($1,680). The $240 savings is the gross benefit. Against it, the $1,440 tied up for an average of six months (the gallons drawn progressively from October to March, so average tied-up period is roughly six months) at a 5% cost of capital is $36 of foregone interest. Net benefit: $204, or 14% on the up-front payment over the holding period. That is a reasonable return for relatively low risk.

The risk is that prices could fall below the pre-buy lock in a particularly weak winter (rare but possible). In the last decade, prices have only fallen below the prior summer pre-buy floor in one or two years. The probability-weighted return on pre-buy remains positive for most homeowners willing to put working capital into the deal.

What summer prices look like in practice

A typical homeowner with a 500-gallon residential tank, billed at the summer fill price, might see a per-gallon quote between $1.55 and $2.00 per gallon depending on region and that summer's wholesale market. The same tank filled in January under will-call pricing might cost $2.40 to $2.90 per gallon. For 400 gallons (a typical fill), that is a difference of $200 to $360 per fill. A 1,000- gallon-per-year household that captures the discount on 80% of consumption saves $200 to $300 per year.

The catch on capturing the discount is tank size and willingness to think ahead. Many homeowners only call the propane dealer when the tank gauge drops below 20%, which is typically October or November when prices are climbing. The discipline of arranging a summer fill in July, when there is no heating demand and the tank is sitting at 30 to 50%, is the lever.

Will summer 2026 be a good fill year?

The 2025-2026 winter ended with US propane inventory rebuilding on normal seasonal pattern and no notable supply stress. The EIA Short-Term Energy Outlook (see our forecast page) anticipates a normal inventory rebuild through the summer with no unusual demand events. Absent a major export surge or hurricane disruption to Gulf Coast fractionation, summer 2026 looks like a reasonable fill year, with the seasonal trough probably reaching its usual August or September low.

Watch the EIA monthly residential figure for May, June, July, and August (published mid-month for the previous month) to track how the trough is developing in real time. The EIA monthly residential is at series M_EPLLPA_PRS_NUS_DPG; the Mont Belvieu daily at our spot price page is the higher-frequency signal.

FAQ

When is the cheapest month to buy propane?

August is the modal annual low month in the EIA monthly residential archive, with September the second most common low month. The annual low has fallen in August or September in 7 of the last 12 years tracked.

How much can I save with a summer fill program?

Typically 15 to 30 cents per gallon versus winter will-call pricing, sometimes more in volatile years. For a 1,000-gallon-per-year household capturing the discount on most of consumption, that is $150 to $300 per year of saving.

Is pre-buy worth the up-front payment?

In most years yes, with a typical 8 to 15% net return on the up-front payment after accounting for cost of capital. The risk is downside price moves, which have been rare in the last decade.

Why does propane peak in winter and trough in summer?

US residential propane demand is dominated by space heating, which is essentially zero May through September. Production runs flat year-round so inventory rebuilds through summer, capping the wholesale price floor.