25th September 2026
The United States is now experiencing something that will be familiar to anyone filling a diesel vehicle in Caithness.
But the numbers are on a different scale.
The average US price of diesel has climbed to around $6.53 a gallon, according to the US Energy Information Administration. AAA recorded a record national average of $6.5276 on September 22.
That works out at roughly $1.72 a litre.
A year ago the US average was around $3.75 a gallon. The latest price is therefore about 74% higher than a year ago.
And some parts of America are experiencing considerably higher prices. The EIA puts the average in California at more than $8.20 a gallon.
This is not simply a story about American motorists paying more at the pump.
Diesel is the fuel that moves much of the modern economy.
Trucks carry food from farms to processing plants and then to supermarkets. Lorries move building materials, machinery and manufactured goods. Farmers use diesel tractors and combines to plant and harvest crops. Construction equipment consumes large quantities of diesel.
So when diesel prices rise sharply, the cost does not necessarily stop at the filling station.
It can eventually appear in the price of goods.
Reuters has reported that American farmers are already being hit particularly hard during the harvest season. One farmer reported that fuelling a single combine could cost as much as $1,500 a day, while the cost of diesel for some farming operations has roughly doubled.
The pressure on American truckers is also becoming severe.
This is important because transport companies cannot always immediately pass the full increase in fuel costs on to their customers. Some operate on contracts agreed before the latest increase. Smaller operators can therefore find themselves squeezed between higher costs and rates that cannot easily be increased.
There is also a worrying supply story behind the price.
US diesel inventories fell to 107.9 million barrels by September 11, the lowest level recorded for that time of year since records began in 1982, according to Reuters.
That helps explain why diesel prices have been rising so rapidly.
The disruption to global fuel supplies associated with the conflict involving Iran, together with attacks on Russian refining capacity, has tightened supplies of refined products. Reuters reports that the global diesel shortage could persist into 2027 if inventories remain under pressure.
And this is where the American situation becomes relevant to Britain.
The United States is a huge fuel market, but it is also part of the same international oil and refined-fuel system. Diesel is traded internationally and refinery capacity is not infinitely flexible.
If refiners, traders and transport companies around the world are competing for limited supplies of diesel, a shortage in one major market can add to pressure elsewhere.
That does not mean that a US record automatically produces another increase at a filling station in Thurso or Wick.
UK prices are affected by crude oil prices, refining margins, exchange rates, taxes, domestic competition and the availability of refined fuel. But the American figures provide another indication of how tight the international diesel market has become.
For businesses, the consequences could be wider still.
A haulage company facing much higher fuel bills may have to increase its charges. A farmer faces higher machinery costs. A construction company pays more to operate equipment. A delivery company faces higher running costs.
Eventually somebody has to absorb those costs.
It may be the business through lower profits. It may be the worker through reduced investment or employment. Or it may be the consumer through higher prices.
It will not necessarily happen immediately. Existing contracts and competition can delay the effect. But if high diesel prices persist, the pressure gradually works its way through supply chains.
That is why diesel deserves attention beyond the forecourt.
A motorist sees a higher number on the pump.
A supermarket sees higher delivery costs.
A farmer sees a larger fuel bill.
A haulage company sees its margins squeezed.
And eventually the consumer may see some of those costs appearing on the price tag.
For Caithness, where distances are greater and many businesses depend heavily on road transport, that final point matters.
The American experience is therefore worth watching.
The question is no longer simply how expensive diesel is today.
It is how long the world can operate with diesel supplies this tight before the cost starts appearing more widely throughout the economy.