CDT: which one do you mean?
CDT means 2 different things, and they are hours apart. If you received a timestamp labelled CDT, the sender's location decides which of these applies, so pick it below.
Central Daylight Time · North America
13:44:35
Sunday, 15 November 2026
- abbreviation denotes
- -05:00
- in force right now
- CST (UTC-06:00)
- use in code
- America/Chicago
- next clock change
- 14 Mar 2027 03:00 → CDT
Right now this zone is on CST, not CDT. They are the same place at different times of year.
Cuba Daylight Time · Caribbean
15:44:35
Sunday, 15 November 2026
- abbreviation denotes
- -04:00
- in force right now
- CDT (UTC-04:00) · DST
- use in code
- America/Havana
- next clock change
- 7 Nov 2027 00:00 → CST
Use the IANA name, not the abbreviation
Python
from datetime import datetime
from zoneinfo import ZoneInfo
# right: an IANA zone carries the full history of rule changes
now = datetime.now(ZoneInfo("America/Chicago"))
print(now.isoformat(), now.tzname())
# wrong: an abbreviation is not resolvable, and a hard-coded offset
# silently rots the next time the rules change
# now = datetime.now(timezone(timedelta(hours=...))) # don'tCDT questions
What does CDT stand for?
CDT has 2 distinct meanings in active use: Central Daylight Time (-05:00, America/Chicago); Cuba Daylight Time (-04:00, America/Havana). Which one applies depends entirely on who wrote the timestamp.
What time is it in CDT right now?
Central Daylight Time: 13:44 on Sunday (CST); Cuba Daylight Time: 15:44 on Sunday (CDT).
Which IANA timezone should I use instead of CDT?
America/Chicago for Central Daylight Time, America/Havana for Cuba Daylight Time. Date libraries cannot resolve bare abbreviations, and an abbreviation carries no daylight-saving history, so a stored offset silently rots when a government changes the rules.
Why does my computer show CST instead of CDT?
Because America/Chicago is currently on CST (UTC-06:00), its daylight-saving variant. CDT (-05:00) applies during the other half of the year. Both names refer to the same place, one hour apart.