CDT срещу CST — каква е разликата?
Същата зона, различен сезон: CDT е лято (UTC −5), CST е зима (UTC −6).
CDT and CST are two faces of the same United States Central time zone. The exact same clock — the one used in Chicago, Houston, Dallas, Minneapolis and the rest of the central U.S. — is called CDT in summer and CST in winter. They differ by exactly one hour.
| CDT | CST | |
|---|---|---|
| Full name | Central Daylight Time | Central Standard Time |
| UTC offset | UTC −5:00 | UTC −6:00 |
| Used when | 2nd Sun of Mar → 1st Sun of Nov | 1st Sun of Nov → 2nd Sun of Mar |
| IANA zone | America/Chicago | America/Chicago |
| Cities | Chicago, Houston, Dallas, San Antonio, Austin, Minneapolis, New Orleans, Memphis, Milwaukee, Kansas City | |
Which is in effect right now?
You can always tell from a current calendar date — but the easiest way is just to check our live CDT clock. If it shows the offset as UTC −5, you're in CDT; if it shows UTC −6, you're in CST.
When does it switch?
- CST → CDT: Second Sunday in March at 02:00 — "spring forward".
- CDT → CST: First Sunday in November at 02:00 — "fall back".
Why two names?
The U.S. has used daylight saving since 1918 (with on-and-off periods). Renaming the zone for the summer half of the year is a bit of legacy that has stuck. Internationally most software just uses the IANA zone America/Chicago and computes the offset for the date you ask about.