Will CPI rise more than 0.8% in December 2026? — Above 0.8%

- [2026-10-14] BLS confirms September CPI-U rose 0.6% seasonally adjusted (m/m) after 0.4% in August. The 12-month rate was 3.7% (NSA), up from 3.4% in August. Gasoline rose 9.1% in the month and accounted for over half of the increase. Energy rose 5.2%. Core rose 0.3%, and core was 2.6% y/y. https://www.bls.gov/news.release/cpi.htm - [2026-10-14] Energy was up 20.4% y/y in September, and food was up 2.5% y/y. Shelter rose 0.4% m/m. https://www.bls.gov/news.release/cpi.htm - [2026-10-17] Monthly headline CPI (SA) in 2026 by month: Apr +0.6, May +0.5, Jun -0.4, Jul +0.1, Aug +0.4, Sep +0.6. No month has reached 0.8 in the series shown. Y/y peaked at 4.2% in May. Median CPI has run 0.2–0.4 monthly. https://www.clevelandfed.org/indicators-and-data/median-cpi - [2026-10-16] Cleveland Fed nowcast for October 2026: CPI +0.27% m/m, core +0.21%, CPI 3.77% y/y. The Q4 annualized CPI nowcast is 4.77%. The page has no November or December monthly nowcast yet. https://www.clevelandfed.org/indicators-and-data/inflation-nowcasting - [2026-10-12] CNBC reported Kalshi traders put just under one-in-three odds on a new 2026 y/y high (above 4.2%). It described inflation as likely peaked but sticky. (Other-strike context only, not this contract.) https://www.cnbc.com/2026/10/12/inflation-will-remain-sticky-in-2026-according-to-prediction-markets.html - [2026-10-17] The Fed raised its rate to 3.75–4% on Sept 16, its first hike since 2023. The next FOMC is Oct 27–28. After the CPI report, traders put the odds of an October hike near 50-50. https://finance.yahoo.com/economy/articles/vanguard-economist-says-sticky-inflation-120300588.html - [2026-10-12] Cleveland Fed President Hammack warned inflation pressures are broadening. She said August PCE was 3.4% y/y and core PCE was 3.0%. https://www.schiffgold.com/commentaries/cleveland-fed-chief-acts-like-an-inflation-hawk-in-latest-speech - [Schedule, per BLS] The remaining CPI releases are October CPI on Nov 10, 2026, November CPI on Dec 10, 2026, and December CPI on Jan 13, 2027 at 8:30 ET. The December release falls on the contract's trading-close date. https://www.bls.gov/schedule/news_release/cpi.htm - [2026-01-13] The December 2025 CPI was +0.3% m/m and 2.7% y/y. This matters only if the contract is read as y/y, in which case the base effect compares against that month. https://www.cnbc.com/2026/01/13/cpi-inflation-report-december-2026.html - [Late 2025] The 2025 federal shutdown disrupted the Oct–Nov 2025 CPI data. The January 2026 CPI release was delayed to Feb 13. The contract's rule allows a delay extension if a shutdown affects the source. I found no sign of a current shutdown affecting the December 2026 release. https://www.nypresswire.com/calendar/cpi-release-schedule-2026 - [Ambiguity] The rule says "CPI increases by more than 0.8% in December 2026". This most plausibly means the m/m SA headline change, which BLS publishes to one decimal. The y/y rate is 3.7% now and would already exceed 0.8%, so the y/y reading would make the contract trivially Yes. I could not confirm the intended reading from the rules text I was given. BOTTOM LINE: The latest m/m prints are 0.6% (Sep) and a nowcast of about 0.27% (Oct), with core steady near 0.2–0.3%. A December m/m above 0.8 would need a much larger energy shock than September's 9% gasoline jump produced. If the contract were read as y/y it would already be above 0.8%, so the resolution wording matters more than the data. NOT FOUND: Cleveland Fed nowcasts for Nov/Dec 2026 m/m. Economist consensus forecasts for December 2026 m/m CPI. Kalshi's official wording clarifying m/m versus y/y. Current gasoline or oil price trends after mid-October.

- [2026-10-14] The September 2026 CPI-U rose 0.6% m/m SA, after 0.4% in August. The 12-month rate was 3.7%. Gasoline rose 9.1% m/m and drove over half of the monthly gain. Core rose 0.3%. https://www.bls.gov/news.release/cpi.htm - [2026-10-16] The 2026 monthly SA CPI path was: Jan +0.2, Feb +0.3, Mar +0.9, Apr +0.6, May +0.5, Jun −0.4, Jul +0.1, Aug +0.4, Sep +0.6. Only one month this year (March, +21% gasoline after the Iran war began and Hormuz closed) printed above 0.8. That is 1 of 9 months. The path is from a secondary summary of BLS data. https://wichitaliberty.org/economics/september-2026-cpi-report - [2026-10-16] The Cleveland Fed nowcast for October 2026 is CPI +0.27% m/m and 3.77% y/y, with core at 0.21%. Q4 CPI is nowcast at 4.77% annualized. I found no nowcast for December itself. https://www.clevelandfed.org/indicators-and-data/inflation-nowcasting - [2026-10-15] The September PPI rose 1.3% m/m, the largest since March 2022. Final demand goods rose 2.6% and energy 10.8%. This is a pipeline upside risk, though energy was the main driver. https://www.bls.gov/news.release/ppi.nr0.htm - [2026-10-14] The reference class is monthly headline CPI prints of 0.9% or higher in the post-1990 era. These are rare and cluster in energy or pandemic shocks: October 2021 was +0.9% (https://www.cnbc.com/2021/11/10/consumer-price-index-october.html) and March 2026 was +0.9%. Outside 1990, 2005 (Katrina), 2008 and 2021–22, prints above 0.8% almost never occur. This is from my background knowledge, not a fetched series. - [2026-10-12] Kalshi traders put under 1-in-3 odds on a new 2026 y/y high (above 4.2%). Their September y/y median was 3.6%, in line with FactSet. https://www.cnbc.com/2026/10/12/inflation-will-remain-sticky-in-2026-according-to-prediction-markets.html - [2026-10-13] A report on Kalshi's year-over-year CPI market (not the m/m strike) says the December 2026 median is about 3.6%. It gives about 64% for above 3.5% and about 21% for above 4.0%. These are sibling-market figures and predate the September print. https://cryptobriefing.com/kalshi-traders-inflation-peaked-2026-sticky/ - [2026-10-17] A tracker citing Kalshi puts the November CPI (released Dec 10) at a 3.8% y/y median. It gives a 37% chance of a print above 3.9%. That implies expected momentum is only modestly positive, with no m/m spike priced in. https://predictionmarketspicks.com/tools/inflation-tracker - [2026-10-14] Consensus and model forecasts for September were close to the actual print (0.6% m/m). Their misses on m/m were about 0.0–0.1pp. BLS cites a 1-month standard error of about 0.04pp, with a confidence margin of roughly ±0.08pp. https://wichitaliberty.org/economics/september-2026-cpi-report - [2026-10-12] Context: the Fed raised rates four weeks ago, for the first time since 2023. Hammack, in a 10/12 speech, called inflation broad-based. One-year household inflation expectations are 3.9%. https://www.tokenpost.com/news/regulation/31966 - Seasonal and base considerations: December CPI is released in mid-January 2027, so the question resolves on the BLS-published December figure. The wording is ambiguous between m/m and y/y. At the 0.8% threshold, m/m SA is the natural reading (a y/y of 0.8% is implausible at about 3.7%). A 0.9%+ m/m would require a new energy shock of March-2026 scale. I did not verify the m/m reading against Kalshi's contract page. BOTTOM LINE: Historically, a monthly CPI print above 0.8% is a tail event, roughly 1 in 9 months in 2026 even in an energy-shock year. Current nowcasts (~0.3% for October) and priced y/y paths imply no spike. The upside tail rests on a further oil/gasoline surge, and September PPI shows that risk is live. NOT FOUND: A December 2026 m/m consensus or nowcast, Kalshi's m/m strike pricing for December, and a fetched long-run historical frequency table of m/m prints above 0.8%.

YES means: the BLS-published December 2026 CPI-U seasonally adjusted one-month change (released Jan 13, 2027, one decimal) is 0.9% or higher. A 0.8% print resolves No. - [2026-10-17] Kalshi's CPI contract terms define the underlying as the signed one-month, one-decimal change in the seasonally adjusted CPI-U. The payout needs a value strictly greater than the strike. So the contract is m/m, and the y/y reading (already 3.7%) is excluded. Only a print of 0.9% or more counts. https://kalshi-public-docs.s3.amazonaws.com/contract_terms/CPI.pdf - [2026-10-17] Brent settled at $109.86 on Oct 16, up 4.9% on the week and the highest since May 19. WTI was $101.41, up 10.4% on the week. The Friday jump came from a missile aimed at the Saudi Red Sea port of Yanbu, a Russian refinery outage, and Eurasia Group raising its escalation odds to 65% from 35%. Brent was in a $104–107 range earlier in the week. This is the strongest live path to YES: a renewed oil spike. https://unbiasednews.substack.com/p/oil-monitor-weekly-summary-brent-a38 - [2026-10-17] Hormuz flows are still impaired. Kpler put the seven-day average at about 68% of the pre-war baseline on Oct 13. One Kpler daily reading showed 2.9 mb transiting on Oct 11, against about 20.8 mb on Oct 8. The IEA warned diesel constraints could last well into next year. Bank oil scenarios span more than $40, with Goldman above $120 if attacks persist. https://unbiasednews.substack.com/p/oil-monitor-weekly-summary-brent-a38 - [2026-10-17] The pump-price lag is a mechanism for a late-year jump. AAA's national average was $4.31 on Oct 17, below the September monthly average of $4.33–4.36. A move in crude to $115 or higher would push retail gasoline well above $4.50 by December, and December's average would be compared against November's. The highest weekly price this year was $4.55 in May, so a fresh record would be needed. https://gasprices.aaa.com/?state=TX - [2026-10-08] Diesel is near $6.3 a gallon, and US distillate stocks are about 14% below the five-year average. That leaves fuel-intensive categories exposed, including freight, airfares and food. It adds to pass-through pressure beyond gasoline itself. https://discoveryalert.com/analysis/hormuz-oil-prices-brent-shipping-risk-october-2026/ - [2026-10-14] The BLS table shows how big energy swings have been this year. Energy commodities rose 21.3% in March, 5.6% in April, 6.7% in May, then fell 9.5% in June. They rose 4.2% in August and 9.3% in September. A 0.9% headline needs roughly energy +9–10% with core at 0.3% and food at 0.3%. September's energy +5.2% produced a 0.6% headline. March's +10.9% energy produced 0.9%. https://www.bls.gov/news.release/cpi.nr0.htm - [2026-10-14] Core is accelerating, which lifts the floor under headline. Core y/y rose to 2.6% in September from 2.4% in August. Shelter was +0.4% in September. A 0.3–0.4% core plus an energy shock lowers the energy increase needed for 0.9%. https://www.bls.gov/news.release/cpi.nr0.htm - [2026-10-17] The oil-price outlook rests on a fragile assumption. Goldman's Q4 call of about $80 oil rested on oil cooling to about $85 by December, and Brent is about $25 above that path. The EIA's October STEO sees Brent averaging $105 in Q4. The oil-price reference used in Admiral's preview shows the shortfall against Goldman's assumption. https://admiralmarkets.com/analytics/traders-blog/us-cpi-september-2026-scenarios-fed-october - [2026-10-17] Sibling-market pricing shows that a hot tail is acknowledged. Kalshi's y/y December ladder gave 21% for above 4.0% as of about Oct 13, before the Oct 16 oil jump. That is still below May's 4.2% peak. This is y/y, not this m/m contract. https://cryptobriefing.com/kalshi-traders-inflation-peaked-2026-sticky/ - [2026-10-17] Policy offsets are weak. The IEA's emergency releases and DOE's SPR exchange are loans and timing relief, not new supply, and barely moved crude. Trump waived the Russia-buyer penalties, which is bearish for crude only at the margin. Congress is trying to block the Russian diesel deal, so supply policy could reverse in either direction. https://unbiasednews.substack.com/p/oil-monitor-weekly-summary-brent-a38 - [2026-10-14] Seasonality matters for December. The BLS adjusts motor fuels with intervention analysis. Seasonal factors usually subtract from December gasoline's NSA movement, so a SA print above 0.8% would need a real, large rise in December gasoline. The Dec 2025 print was just 0.3%, so no December seasonal quirk favors a spike. https://www.bls.gov/news.release/archives/cpi_01132026.htm BOTTOM LINE: The single most likely path to YES is a Hormuz/Red Sea escalation in November–December. It would need Brent to break about $115–120 and retail gasoline to rise roughly 10% or more in December alone, with core at 0.3% or higher. That has happened once this year (March, +0.9%), and the Oct 16 oil jump makes the tail live, but it needs a fresh shock beyond what is priced. NOT FOUND: Any December m/m consensus or nowcast. Kalshi's current price for this m/m strike (deliberately not searched). A fetched long-run table of 0.9%+ prints. Oil prices after Oct 17 close.

YES means: BLS reports the December 2026 CPI-U seasonally adjusted one-month change as 0.9% or more. That is "strictly greater than 0.8" at one decimal. It does not mean the y/y rate. - [2026-10-18] **Reading of the rule.** Kalshi's CPI contract terms define the Underlying as the signed one-month, one-decimal percent change in seasonally adjusted CPI-U. A y/y reading is therefore ruled out, and my colleagues' ambiguity worry is resolved. The payout requires a value strictly greater than the strike, so a print of exactly 0.8 resolves NO. The terms also say later revisions don't count, so only the first print on the Jan 13, 2027 release matters. https://kalshi-public-docs.s3.amazonaws.com/contract_terms/CPI.pdf - [2026-10-18] **Fallback clause.** If no data is available at expiration, the contract uses a formula based on the 12-month change. That is the 12th root of (latest CPI / CPI 12 months earlier), minus 1. With y/y near 3.7% this gives about 0.3% a month, which is below the strike. The expiration date can be pushed out up to three months after the scheduled release. A delay therefore points to NO, not Yes. https://kalshi-public-docs.s3.amazonaws.com/contract_terms/CPI.pdf - [2026-10-16] **Retail gasoline has plateaued, not accelerated.** AAA's national average was $4.33 on Oct 15, down from $4.41 on Oct 1 and $4.36 on Oct 8. The September monthly average was $4.33, a record. October is therefore tracking roughly flat to slightly lower versus September's average, which is consistent with the Cleveland Fed's +0.27% October nowcast. The 9.1% September gasoline jump is not repeating. https://gasprices.aaa.com/news/ - [2026-10-16] **Wholesale gasoline is falling.** RBOB-type gasoline futures were about $3.24/gal on Oct 16, down 7.7% over the past month. They hit a 5-week low of $3.09 during the month, and a two-week low on Oct 15 on a US proposal to ease sanctions on shadow-fleet tankers. A 0.9%+ December headline would need a sharp new shock between now and mid-December, on top of a market that is currently softening. https://tradingeconomics.com/commodity/gasoline - [2026-10-12] **Brent is high but flat.** Brent was $108.04 on Oct 12 and $108.51 on Oct 16, versus $109.73 a month earlier. A level that has held for a month does not push the monthly change much. A December spike needs a further leg up, not a continuation. https://fortune.com/article/price-of-oil-10-16-2026/ - [2026-10-06] **EIA expects a plateau, then a decline.** The October STEO has Brent averaging $105 in Q4 2026 and $84 in 2027. Retail gasoline averaged $4.35 in September and is forecast at about $3.56 for 2027. A path that is flat then falling points to flat-to-negative energy contributions around the turn of the year. The STEO also says Middle East flows are expected to increase. https://www.eia.gov/outlooks/steo/pdf/steo_full.pdf - [2026-10-14] **Arithmetic needed for 0.9%.** Core is running about 0.2–0.3% (core was 0.3% in September). Energy is about 7% of CPI by weight, and the September energy index rose 5.2% against a 0.6% headline. To reach 0.9% with core at 0.3%, energy would need to rise roughly 9–10% in December alone, with food and shelter also firm. March 2026 got there with energy +10.9% and gasoline +21.2%. Even April's +5.4% and May's +7.0% gasoline moves produced only +0.6% and +0.5%. https://www.bls.gov/news.release/cpi.htm - [2026-10-14] **Seasonal and revision structure.** The seasonally adjusted December 2025 print was a calm +0.3%. The settling value is the initial SA print, with no allowance for later revisions, so the 0.8 strike would be crossed only by a genuine shock in the first release. BLS-cited sampling error is only about ±0.08pp, which gives little scope for a lucky rounding up. https://www.bls.gov/news.release/archives/cpi_01132026.htm - [2026-10-15] **Status quo is the pattern.** In 2026 only 1 of 9 months printed above 0.8 (March), and it was the Hormuz-closure month. Since then, energy has fallen back (June −5.7%) and re-risen without any monthly headline beating 0.6. The war has already run seven-plus months. Markets have repeatedly adjusted to Hormuz news (the Apr 8 ceasefire, a May 20% oil drop, and Brent under $72 on Jun 26) and are now back near $108. Escalation and de-escalation both seem to be priced in gradually, not as a one-month +9%. https://www.cnbc.com/2026/06/26/oil-prices-middle-east-iran-strait-of-hormuz-opec-iraq-wti-brent-crude.html - [2026-10-13] **Sibling pricing implies no spike.** The y/y Kalshi strike for December 2026 had a median near 3.6%, with about 21% above 4.0%. These figures predate the September print, so treat them as stale. With a December 2025 base of +0.3%, 3.6% y/y by December implies October through December averaging below about 0.3% a month. Hitting 4.0% would need only moderate months, not a 0.9%. https://cryptobriefing.com/kalshi-traders-inflation-peaked-2026-sticky/ - [2026-10-18] **Mechanical check on the sibling-market implications.** A 0.9% December print on top of about 0.27% in October and a typical November would push y/y to roughly 4.3–4.5%. That is above the 4.2% peak, which traders put under one in three. So the tail needed for Yes sits inside the thin upper tail of sibling markets. This is my own arithmetic, not a source figure. https://www.cnbc.com/2026/10/12/inflation-will-remain-sticky-in-2026-according-to-prediction-markets.html BOTTOM LINE: Under Kalshi's own terms the contract is the SA m/m headline change, which must be at least 0.9%. Gasoline has plateaued and wholesale prices are softening, and only one month this year (March) exceeded 0.8. Delay or no-data fallbacks also resolve NO, so Yes needs a fresh March-scale energy shock in Nov–Dec. NOT FOUND: A Cleveland Fed or consensus forecast for November or December 2026 m/m. Current Kalshi pricing for this m/m strike (deliberately not sought). The AAA page itself (403 on fetch; the figures come from the search snippet). A full historical frequency table of m/m prints above 0.8.