Cron for Spring DST Check (Second Sunday of March)

The cron expression 30 2 8-14 3 0 is intended to target the second Sunday of March at 2:30 AM, near the US spring daylight saving time transition.

Field-by-field breakdown:

• 30 (Minute): At minute 30. The task fires at the half-hour mark.
• 2 (Hour): At hour 2 (2 AM). This is the hour when US daylight saving time springs forward (clocks jump from 2:00 AM to 3:00 AM).
• 8-14 (Day of Month): Days 8 through 14 of the month. The second Sunday of any month always falls within this range.
• 3 (Month): In March only. This targets the month when spring DST occurs in the US.
• 0 (Day of Week): Sunday only. The value 0 represents Sunday.

Important caveat: As with other expressions combining Day of Month and Day of Week, standard cron uses OR logic, so this fires on ALL Sundays in March AND on days 8-14 regardless of day. Add a script guard for precision. Additionally, 2:30 AM may not exist during spring forward (clocks skip from 2:00 to 3:00), so this job may be skipped entirely by the cron daemon on that date. This expression is educational: it demonstrates the challenges of scheduling around DST transitions. Most cron implementations will either skip the job or run it at 3:00 AM instead. This expression is supported by standard cron on Linux/macOS, as well as cloud services like AWS CloudWatch, Google Cloud Scheduler, and GitHub Actions.