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Understanding time zones can be surprisingly tricky. Things quickly get complicated with daylight saving time, half-hour offsets, and regions that don’t follow the rules. Whether you’re scheduling interviews across continents or just trying to avoid confusion, this guide breaks down how time zones work—and where they often get tricky.

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In This Article

How Time Zones Work

• The Earth is divided into 24 time zones, generally one for each hour of the day.
• Time zones are based on UTC (Coordinated Universal Time). Local times are usually written as UTC+X or UTC–X.
• Daylight Saving Time (DST): Many regions move the clock forward in spring and back in fall, but not all.

Where it Starts to Get Confusing

Daylight Saving Time (DST)

• Start and end dates vary by country and sometimes region.
  • Example: US switches in March/November, Europe in March/October.

Time Zone Abbreviations Can Be Ambiguous

• Be sure to check the IANA time zone name, like Chicago

  • Example: CST = Central Standard Time (US) or China Standard Time

  

Common Scheduling Gotchas

1. Phoenix, Arizona
   • Does NOT observe DST, stays on Mountain Standard Time (MST) year-round.
   • In summer, Phoenix aligns with Pacific Time; in winter, with Mountain Time.
2. Hawaii
   • No DST, always UTC–10.
   • Can be up to 6 hours behind Eastern Time, but only 5 in winter.
3. Parts of Australia
   • Different states observe DST or not (e.g., Queensland does not, New South Wales does).
   • Their summer is opposite the Northern Hemisphere (December–February).
4. Newfoundland, Canada
   • Uses a half-hour offset: UTC–3:30.