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Keeping Time Zone Data Updated

IANA tzdata releases, OS patches, and handling Mexico/Turkey rule changes.

The IANA tz database updates many times per year when countries drop DST, add zones, or fix history. Stale OS, server, or runtime data causes "right date, wrong clock" — especially after changes in Mexico Time Zones Guide and Worldwide Daylight Saving Abolition Trends.

What to update

  • OS: Windows/macOS/iOS/Android system updates
  • Servers: Linux tzdata packages; rebuild Docker images
  • Runtimes: Node.js, JVM, Python zoneinfo via patches
  • Browsers: generally follow OS tz data

Best practice

  • Track IANA and OS security advisories in production
  • Store UTC/timestamps; convert with What Is the IANA Time Zone Database IDs in UI
  • Regression-test Convert after policy news
  • Never hardcode "country always UTC+X" forever

Basics: UTC Basics, Unix Timestamps and UTC; devices: Phone and Computer Time Zone Settings.