The Prairies gave August back. As of August 31, 2026, the average price of regular across the 78 Costco gas bars we track in Canada is 164.6¢ a litre — down 6.9¢, or 4.0%, from 171.5¢ on August 1. Saskatchewan led the country lower, down 23.0¢ (−14.4%), with Manitoba and Alberta each off more than 17¢. Ontario was the exception that rose, up 3.3¢. Diesel, sold at six warehouses, went the other way: up 11.3¢ (+5.8%) to 206.7¢. It is the inverse of July, when the Prairies flipped from biggest faller to biggest riser — and it sits next to a mixed month in the U.S., the UK, and Australia.
| Grade | August 1 | August 31 | Month change |
|---|---|---|---|
| Regular | 171.5¢ | 164.6¢ | ▼ 6.9¢ (4.0%) |
| Premium | 194.0¢ | 186.8¢ | ▼ 7.2¢ (3.7%) |
| Diesel | 195.4¢ | 206.7¢ | ▲ 11.3¢ (5.8%) |
National averages of posted prices at tracked Costco gas bars in Canada, ¢/L. Snapshot of calendar August 2026 — this article is not updated.
A slide to August 7, then a choppy climb that still finished cheaper
Regular fell from 171.5¢ on August 1 to a low of 155.4¢ on August 7 — the cheapest national reading of the month, and a 16¢ drop in a week. From there it bounced, held in the high 150s, then climbed into the mid-160s by August 21. The last ten days chopped between 161¢ and 166¢ and closed at 164.6¢: 9¢ off the trough, still 7¢ cheaper than the start of the month. Of 78 gas bars, 52 finished cheaper, 22 dearer, and 4 were unchanged.
The Prairies led the drop; Ontario was the only riser
Last month Manitoba and Alberta were the bounce. This month they unwound it. Saskatchewan's Costco average fell 23.0¢ to 136.9¢, the cheapest province we track, with Regina at 131.9¢ the cheapest pump in the country. Manitoba dropped 19.3¢ and Alberta 17.9¢; South Calgary at 139.9¢ is back among the cheapest warehouses. British Columbia fell 10.4¢ even as Langley, at 199.9¢, remains the priciest bar we track. Kelowna cut 32¢ — the biggest station move in the country. Ontario went the other way: up 3.3¢, led by Scarborough, Niagara Falls, and Ajax, each adding 10¢.
Biggest fallers
| Province | Avg now | Change |
|---|---|---|
| Saskatchewan | 136.9¢ | ▼ 23.0¢ (14.4%) |
| Manitoba | 146.6¢ | ▼ 19.3¢ (11.7%) |
| Alberta | 145.3¢ | ▼ 17.9¢ (11.0%) |
| British Columbia | 176.4¢ | ▼ 10.4¢ (5.6%) |
| Quebec | 177.0¢ | ▼ 6.3¢ (3.4%) |
Biggest risers
| Province | Avg now | Change |
|---|---|---|
| Ontario | 168.4¢ | ▲ 3.3¢ (2.0%) |
Ontario was the only province that rose. Newfoundland was unchanged at 194.9¢.
Biggest August movers by province-average price of regular at Costco, August 1 – 31, 2026.
Every province, ranked by August 31's Costco average
The country's spread is wide again: 58.0¢ a litreseparates Saskatchewan's 136.9¢ from Newfoundland's 194.9¢. At the station level, Regina at 131.9¢ sits 68¢ below Langley, B.C. British Columbia is no longer the outright dearest province on average — Quebec and New Brunswick sit just above it — but the most expensive individual pumps are still on the West Coast.
| Province | Gas bars | Costco avg (regular) |
|---|---|---|
| Saskatchewan | 3 | 136.9¢ |
| Alberta | 17 | 145.3¢ |
| Manitoba | 3 | 146.6¢ |
| Ontario | 27 | 168.4¢ |
| British Columbia | 8 | 176.4¢ |
| Quebec | 17 | 177.0¢ |
| New Brunswick | 2 | 179.4¢ |
| Newfoundland and Labrador | 1 | 194.9¢ |
Province-average price of regular across tracked Costco gas bars, August 31, 2026.
Why the Prairies fell — and why diesel did not
Canadian pumps spent August with the federal fuel-excise holiday still in force — 10¢/L off gasoline and 4¢/L off diesel through early September — so the national print was already running below a full-tax market. On top of that, wholesale racks in the Prairies unwound July's bounce: the same provinces that mean-reverted higher last month gave it back, which is why Saskatchewan, Manitoba, and Alberta dominate the fallers table. Ontario's 3.3¢ rise is the other half of that regional split, not a national uptrend.
Diesel is the same distillate story as in the U.S.: six Costco diesel bars climbed 11.3¢ even as regular fell 6.9¢. The holiday's 4¢ diesel cut is smaller than the 10¢ gasoline cut, and heating-oil-linked cracks stayed firm, so the grade that was July's star faller is August's only riser.
The 4% drop has an expiry date
The federal excise holiday ends in early September. Rolling 10¢ back onto gasoline — and 4¢ onto diesel — would more than erase August's 6.9¢ regular decline on its own, before racks move. Alberta's fuel-tax review is the other fixed date on the calendar. The 155.4¢ trough on August 7 may be the cheapest national Costco print of the summer.
Will gas prices keep falling?
Not if the holiday lapses on schedule. The EIA outlook still treats Hormuz shipping as the swing for North American racks; Canadian pumps follow those racks with a lag of days. Layer the two Canadian dates — the excise holiday and Alberta's tax review — on top of a diesel grade that already rose 5.8%, and the risk into September is tilted toward higher pump prices even if crude behaves. Saskatchewan at 136.9¢ is the place the club discount is doing the most work; Newfoundland at 194.9¢ is still its own market.
Costco pump prices are a snapshot of calendar August 2026 (August 1–31) and will differ at the pump today. A handful of GasBuddy rows on August 6–7 arrived in dollars per litre rather than cents; those readings were rescaled to ¢/L before averaging. This site is independent and not affiliated with Costco Wholesale Corporation.
