The Weekly Fill-Up | September 14-18

September 14, 2026

Harvest is beginning across parts of the country, and the energy markets are entering the season with a noticeable divide.

Diesel has become considerably tighter and more expensive over the past few weeks. Propane, meanwhile, continues to enter fall with a substantial amount of product in storage. For Sioux Valley Coop members, those opposing market conditions make it especially important to look at each part of the operation separately as harvest activity increases across eastern South Dakota.

Diesel Supply Has Become the Market to Watch

The diesel outlook has changed considerably since the end of August.

The U.S. Energy Information Administration released its September Short-Term Energy Outlook on September 9, and its forecast deserves attention from agricultural diesel users. EIA now expects U.S. distillate inventories to fall below 100 million barrels during September and remain below the lowest levels seen during the previous five years through the end of 2026 and much of 2027.

That is a significant change in the supply environment.

Actual inventories did receive some relief during the latest reporting period. U.S. distillate stocks increased from approximately 104.2 million barrels on August 28 to 106.3 million barrels on September 4. Midwest inventories, however, moved slightly lower from about 28.8 million to 28.5 million barrels.

The concern isn’t simply one week’s inventory movement. It’s the broader global supply picture.

Diesel production has been disrupted in several major refining regions, while strong international prices have encouraged U.S. refiners to export more product. Industry executives told Reuters last week that global diesel supplies could remain tight through the winter because of limited spare refining capacity and reduced supplies from Russia and other producing regions.

The effects are already showing up at the pump. Reuters reported on September 10 that the national average retail diesel price surpassed $6 per gallon for the first time.

For Sioux Valley Coop members, the takeaway is not to panic over one price movement. It is to recognize that harvest is beginning during a genuinely tight diesel market.

Bulk fuel planning becomes particularly valuable under these conditions. Producers who have a reasonable estimate of their harvest fuel requirements can communicate those needs early and make sure on-farm storage is positioned for the workload ahead.

Propane Enters Fall From a Much Stronger Position

The propane market provides a welcome contrast.

U.S. propane and propylene inventories reached approximately 110.5 million barrels for the week ending September 4. Midwest inventories stood at approximately 26.6 million barrels.

That is a strong supply base as the industry moves out of summer inventory-building season and toward fall demand.

But September also marks the point when propane inventories begin facing their first real tests.

Grain drying is one of them.

USDA’s latest national Crop Progress report showed corn harvest beginning to accelerate, with 5% of the U.S. crop harvested as of September 6. South Dakota’s current production outlook includes approximately 5.84 million acres of corn expected to be harvested for grain.

How much propane that crop requires will depend heavily on moisture when it comes out of the field.

A warm and dry September can allow corn to lose moisture naturally before harvest. A wetter finish can shift more of that work to grain dryers, creating concentrated propane demand across agricultural areas.

That’s why the next few weeks will tell us much more about the actual strength of the fall propane market.

Propane Contracting Still Has a Role

Strong inventories can make it tempting to assume propane prices will remain favorable throughout the fall and winter. Inventory is only one part of the equation.

Grain drying, winter temperatures, exports, transportation capacity, and regional demand can all influence what customers ultimately pay.

For customers who know propane will be part of their winter budget, contracting remains an option for reducing some of that uncertainty.

Sioux Valley Coop offers 100% prepay, no-money-down, and consumption-billing contract options. Consumption billing can be especially useful for customers who want the security of a contract without paying for the entire contracted amount upfront, because they pay as the propane is actually used.

The goal of contracting isn’t necessarily to beat the market. It’s to make an important farm, home, or business expense more predictable.

Bulk Oil: September Is a Good Time to Take Advantage of Savings

There is another timely opportunity for Sioux Valley Coop customers this month that has nothing to do with predicting energy markets.

SVC’s fall bulk oil promotion is underway throughout September, with customers able to save more than $1 per gallon on delivered bulk oil.

The timing lines up well with harvest.

Instead of waiting until equipment reaches its next service interval in the middle of the season, producers can review what they expect to use now and replenish bulk supplies while the promotion is available.

Engine oil is only one part of that conversation. Hydraulic systems and other heavily used components will also accumulate hours quickly once harvest is underway. Having the correct products available on the farm reduces another potential source of downtime when the operating window becomes tight.

For operations already purchasing lubricants in volume, September offers an opportunity to combine maintenance planning with actual per-gallon savings.

Harvest Is Turning Forecasts Into Actual Demand

For much of the summer, we’ve talked about what could happen once harvest arrived.

We’re now reaching the point when those forecasts start becoming real demand.

Combines and tractors will begin consuming diesel. Trucks will move grain from fields to bins and elevators. Grain dryers may begin consuming propane. Equipment hours will accumulate rapidly, bringing lubricant and maintenance intervals with them.

That makes the current market particularly interesting.

Diesel enters the season with genuine global supply concerns. Propane enters it with strong inventories but an unknown amount of grain-drying and heating demand ahead. Bulk oil needs are becoming operational rather than theoretical as equipment moves into the field.

For Sioux Valley Coop members, September is less about trying to predict the next market move and more about making sure the operation is positioned for the work ahead.

Know how much bulk fuel you expect to use. Pay attention to crop moisture as harvest approaches. Consider whether propane contracting fits your operation or household. Take advantage of the September bulk oil promotion if additional lubricant inventory will be needed.

Harvest has a way of turning weeks of preparation into very long days very quickly. Having the energy side of the operation ready before those days arrive can make a meaningful difference.

Sources

U.S. Energy Information Administration (EIA) – Short-Term Energy Outlook, September 9, 2026
U.S. Energy Information Administration (EIA) – Weekly Petroleum Status Report, September 10, 2026
U.S. Energy Information Administration (EIA) – U.S. and Midwest Distillate Fuel Oil Stocks, week ending September 4, 2026
U.S. Energy Information Administration (EIA) – U.S. and Midwest Propane/Propylene Stocks, week ending September 4, 2026
USDA National Agricultural Statistics Service (NASS) – 2026 South Dakota Agriculture Overview, updated September 12, 2026
USDA NASS – Crop Progress Report, week ending September 6, 2026
Reuters – Global Diesel Supply Expected to Remain Tight Through Winter, September 8, 2026
Reuters – U.S. Average Diesel Price Surpasses $6 per Gallon, September 10, 2026