ACST: Australian Central Standard Time
ACST is Australian Central Standard Time, +09:30, used in Oceania. In code, use Australia/Adelaide rather than the abbreviation.
Australian Central Standard Time · Oceania
09:31:29
Sunday, 15 November 2026
- abbreviation denotes
- +09:30
- in force right now
- ACDT (UTC+10:30) · DST
- use in code
- Australia/Adelaide
- also valid
- Australia/Darwin
- next clock change
- 4 Apr 2027 02:00 → ACST
Right now this zone is on ACDT, not ACST. They are the same place at different times of year.
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("Australia/Adelaide"))
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'tACST questions
What does ACST stand for?
ACST is Australian Central Standard Time, +09:30, used in Oceania. The IANA zone to use in code is Australia/Adelaide.
What time is it in ACST right now?
Australian Central Standard Time: 09:31 on Sunday (ACDT).
Which IANA timezone should I use instead of ACST?
Australia/Adelaide for Australian Central Standard 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 ACDT instead of ACST?
Because Australia/Adelaide is currently on ACDT (UTC+10:30), its daylight-saving variant. ACST (+09:30) applies during the other half of the year. Both names refer to the same place, one hour apart.