Answer: No, there is no upcoming leap second; the bulletin states that no leap second will be introduced at the end of December 2026.
Status: Confirmed
Entry: science/leap-second
Revision: 1
Digest: sha256:5072ffdfe1d6e86f (changes whenever the content changes)

Timeline:
  Created: 2026-11-12T10:44:39Z
  Last changed: 2026-11-12T10:44:39Z
  Last verified: 2026-11-12T11:34:18Z
  Next check: 2026-11-19T11:34:18Z
  Check interval: Weekly
  Expected change: No fixed schedule

Data:
  Field | Value | Unit | Source | As of
  leap second announcement | NO leap second will be introduced at the end of December 2026 |  | [1] | 2026-11-12
  bulletin number | Bulletin C 72 |  | [1] | 2026-11-12
  release date | 06 July 2026 |  | [1] | 2026-11-12
  UTC-TAI difference | -37 s | s | [1] | 2026-11-12

Sources:
  [1] IERS. "datacenter.iers.org/data/latestVersion/bulletinC.txt". https://datacenter.iers.org/data/latestVersion/bulletinC.txt
      Role: primary. Accessed: 2026-11-12T11:34:18Z
      Quote: "NO leap second will be introduced at the end of December 2026." (Supports: leap second announcement)
      Quote: "Bulletin C 72" (Supports: bulletin number)
      Quote: "Paris, 06 July 2026" (Supports: release date)
      Quote: "from 2017 January 1, 0h UTC, until further notice : UTC-TAI = -37 s" (Supports: UTC-TAI difference)
      Published: 2026-07-06T07:53:13Z
      Snapshot SHA-256: 310e172eadacacca3adf92cb9bd646fcc0d6320e35e996a106d2644ede3b52f0 (captured 2026-11-12T10:44:39Z)

Verification:
  Method: Automated extraction from [1] with deepseek-flash (JSON output, thinking disabled). Every value was checked by code to appear verbatim in a quoted passage of [1]. On this check the text of [1] was unchanged since 2026-11-12T10:44:39Z, so the values verified then were kept.
  Cross-check: not-available at 2026-11-12T11:34:18Z. No independent second source is configured for this entry
  Last successful check: 2026-11-12T11:34:18Z
  Last attempt: 2026-11-12T11:34:18Z

Notes and limitations:
  Extracted automatically from a single official source.

Change log:
  Time | Event | Change | Source
  2026-11-12T10:44:39Z | added | Entry created | —
  Changes for this entry as a feed: https://latestn.com/science/leap-second/latest

Challenge this entry:
  Open challenges: None
  How: If a value here is wrong or out of date, send what is wrong and a link to evidence. Challenges are queued and checked against the evidence; they do not change the entry by themselves. If the entry changes as a result, the change log says so.
  Form: https://latestn.com/dispute/science/leap-second
  POST: https://latestn.com/dispute/science/leap-second with claim, evidence_url, and optionally field and contact (form-encoded or JSON)
  GET: https://latestn.com/dispute/science/leap-second?claim={what is wrong}&evidence_url={link}

How to cite:
    latestN. (2026). Is there an upcoming leap second? Revision 1, last verified 2026-11-12T11:34:18Z. https://latestn.com/science/leap-second (accessed 2026-11-12T12:52:48Z).

    @misc{latestN_science_leap_second_r1,
      title        = {Is there an upcoming leap second?},
      author       = {{latestN}},
      year         = {2026},
      howpublished = {\url{https://latestn.com/science/leap-second}},
      note         = {Revision 1; digest sha256:5072ffdfe1d6e86f; last verified 2026-11-12T11:34:18Z; accessed 2026-11-12T12:52:48Z}
    }

URL: https://latestn.com/science/leap-second