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The Weekly Fill-Up | September 15-19

Energy markets this week are defined by both volatility and cautious optimism. In eastern and northeastern South Dakota, along with the Harrisburg area, fuel demand is being driven by the transition into harvest season while propane and DEF markets continue to reflect broader national and global forces. Here’s what matters most for Sioux Valley Coop members.

Oil Prices Tugged Between Tension and Oversupply

Oil prices have trended upward to start the week, with Brent crude holding around $67 per barrel and West Texas Intermediate near $63. Gains have been supported by geopolitical tensions, including recent attacks on Russian energy facilities, which raised concerns about global supply. However, market fundamentals show signs of oversupply and weaker U.S. demand, which have kept inventories elevated and capped some of the upward price momentum. Analysts at S&P Global project that crude may soften toward $55 per barrel by the end of the year, suggesting long-term pressure could weigh on retail fuel prices as we move into 2026.

Diesel Costs Hit Harvest Season

For South Dakota, especially in our eastern and northeastern region, diesel is commanding extra attention as farmers head into harvest. National diesel prices reached an average of $3.73 per gallon in early September, up about 11 cents from last year. That increase is being felt locally in Watertown, Webster, Roslyn, and Harrisburg, where agricultural demand is intensifying. Gasoline, on the other hand, has seen only modest post-Labor Day movement, with Midwest averages around $3.08 per gallon. This relative stability helps offset rising diesel costs, though members should expect continued volatility through the fall season.

Propane: A Window of Stability

Propane pricing remains steady in our service areas, with eastern South Dakota averaging near $1.90 per gallon. While statewide averages can mask local conditions, our cooperative territory is showing consistency thanks to healthy inventories and stable supply chains. On the national level, residential propane has edged slightly higher, with the U.S. average now near $2.46 per gallon. Wholesale markets have softened compared to last year, which provides some reassurance as heating season approaches. For members in Harrisburg and across our eastern communities, now is an ideal time to consider budget programs to lock in cost certainty ahead of the colder months.

DEF: Planning Ahead Pays Off

Diesel exhaust fluid continues to be a point of concern. U.S. production constraints, combined with global urea market tightness, are limiting availability. For fleets and farm operations in our region, this means DEF remains firm in pricing, with little indication of immediate relief. Since DEF demand rises alongside diesel use during harvest and transport season, Sioux Valley Coop encourages members to plan ahead and secure supply to avoid potential shortfalls during peak operations.

Staying Powered Locally

This week’s market dynamics reflect the balancing act between global supply concerns and local seasonal demand. Oil prices remain sensitive to geopolitical events, diesel is trending higher year-over-year, propane is steady with slight national increases, and DEF continues to face structural supply constraints. For members across eastern South Dakota, the key to navigating these markets will be proactive planning—securing supply, managing budgets, and leaning on cooperative resources to remain powered locally.

Sources

  • Reuters – Oil extends gains after attacks on Russian energy facilities (Sept 15, 2025)
  • Reuters – Oil prices flat amid weak US demand, softening economy (Sept 11, 2025)
  • Reuters – Oil prices extend losses on oversupply, US demand concerns (Sept 12, 2025)
  • MRT / EIA – Gasoline price forecasts and short-term outlook (Sept 2025)
  • ConsultEnergy.org – South Dakota propane prices (Sept 2025)
  • NPGA / EIA – Weekly Heating Oil and Propane Update (Sept 2025)
  • South Dakota DOT – Fuel Price Index for South Dakota wholesale fuels (Sept 2025)