datetime Basics (Timezones, Pitfalls)

Naive vs Aware

Timezone bugs are common incident causes. Avoid mixing naive and timezone-aware datetimes.

Prefer UTC Internally

from datetime import datetime, timezone

now_utc = datetime.now(timezone.utc)
print(now_utc.isoformat())

Parse and Format ISO 8601

from datetime import datetime

ts = "2026-02-24T10:30:00+00:00"
dt = datetime.fromisoformat(ts)
print(dt.isoformat())

Convert for Display

from datetime import timezone
from zoneinfo import ZoneInfo

dt_utc = datetime.now(timezone.utc)
dt_tr = dt_utc.astimezone(ZoneInfo("Europe/Istanbul"))
print(dt_tr.isoformat())

Operational Checklist

• Store timestamps in UTC; convert only at the edges (UI/reporting).
• Never compare naive and aware datetimes.
• Use ISO 8601 for interchange and logs.

Failure Modes

• DST shifts: local time repeats or skips, breaking schedules.
• Naive timestamps: time math becomes ambiguous across regions.