Cron Daily at Noon

0 12 * * *

At 12:00

Field by Field

Field	Value	Matches
Minute	0	0
Hour	12	12
Day of month	*	every day
Month	*	every month
Day of week	*	every day

Noon Is Hour 12, Midnight Is Hour 0

Cron's hour field is 0–23, so noon is 12 and midnight is 0. There is no 24, and no am or pm. 0 12 * * * is noon; 0 0 * * * is midnight.

The most common error is writing 12 0 * * *, which means "minute 12 of hour 0" — twelve minutes past midnight, twelve hours from what was intended.

Midday Jobs Compete With Traffic

For a consumer product noon is often a daily peak. A report that re-aggregates the whole day's data at 12:00 sharp is doing heavy database work during the busiest window.

If the output is read after lunch rather than at exactly noon, 0 11 * * * gets the same result an hour earlier and out of the way.

Time Zone Sensitivity Is Higher Here

Nobody cares whether a 3am job drifts by an hour. A "midday" job that fires at 4am after a UTC deployment is immediately, visibly wrong — which is at least easy to catch.

Time Zones

Standard crontab evaluates in system local time. Vercel Cron, GitHub Actions, Kubernetes CronJobs and AWS EventBridge all evaluate in UTC. If converting your local time crosses midnight, the day-of-week field shifts too — weekdays at 5pm in UTC-07:00 is 0 0 * * 2-6, not 0 0 * * 1-5.

The Day-Field Trap

When both the day-of-month and day-of-week fields are restricted, cron matches either, not both. 0 0 13 * 5 runs on every 13th *and* every Friday — not Friday the 13th. Leave one of them as * unless you genuinely want the union.

Other Common Schedules

Expression	Runs
* * * * *	Every minute
*/5 * * * *	Every 5 minutes
*/15 * * * *	Every 15 minutes
0 * * * *	Every hour, on the hour
0 0 * * *	Every day at midnight
0 9 * * *	Every day at 9am
0 9 * * 1-5	Weekdays at 9am
0 9 * * 1	Every Monday at 9am

Making the Job Safe

• Assume double firing. DST transitions, restarts and retries all cause it. Make the job

idempotent rather than assuming exactly-once.

• Assume overlap. Cron starts the next run whether or not the last one finished. Take a

lock.

• Avoid :00. Every hourly job on the internet fires at the top of the hour; a random

minute spreads load on shared APIs.

• Log the start and end. A cron job that silently stops running is invisible until

someone notices the missing output.