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Apache Airflow cron expression: twice a day at 9am and 9pm
To run a Apache Airflow job twice a day at 9am and 9pm, use:
0 9,21 * * *At minute 0, during hours 09, 21.
Your week at a glance
Upcoming runs
| # | Local | UTC | From now |
|---|
Copy-ready code
Why use this schedule
A morning and an evening run. Listing the two hours with a comma keeps the intent obvious to the next person reading the config, which matters more than saving a few characters.
- Morning and evening status reports
- Syncing inventory before and after business hours
- Refreshing a feed twice daily
First runs, as an example
Starting from 1 January 2027, evaluated in UTC:
| # | Date and time (UTC) |
|---|---|
| 1 | Fri, 01 Jan 2027, 09:00:00 |
| 2 | Fri, 01 Jan 2027, 21:00:00 |
| 3 | Sat, 02 Jan 2027, 09:00:00 |
| 4 | Sat, 02 Jan 2027, 21:00:00 |
| 5 | Sun, 03 Jan 2027, 09:00:00 |
| 6 | Sun, 03 Jan 2027, 21:00:00 |
Twice a day at 9am and 9pm in every dialect
| System | Expression |
|---|---|
| Apache Airflow (this page) | 0 9,21 * * * |
| Quartz | 0 0 9,21 * * ? |
| Spring | 0 0 9,21 * * * |
| Crontab | 0 9,21 * * * |
| Kubernetes | 0 9,21 * * * |
| AWS EventBridge | 0 9,21 * * ? * |
| Jenkins | H 9,21 * * * |
| GitHub Actions | 0 9,21 * * * |
| node-cron | 0 9,21 * * * |
| Azure Functions | 0 0 9,21 * * * |
| Google Cloud Scheduler | 0 9,21 * * * |
Need to translate a different expression? Use the cron converter.
Ready-to-use Apache Airflow config
Drop this into your project. The expression is the one above.
from datetime import datetime
from airflow import DAG
from airflow.operators.empty import EmptyOperator
with DAG(
dag_id="my_dag",
start_date=datetime(2026, 1, 1),
schedule="0 9,21 * * *", # schedule_interval= before Airflow 2.4
catchup=False,
):
EmptyOperator(task_id="start")The Apache Airflow fields, in order: minute (0-59), hour (0-23), day-of-month (1-31), month (1-12), day-of-week (0-7, 0 and 7 = Sunday).
Things to watch out for in Apache Airflow
- A scheduled run starts after its data interval ends, so a daily 0 0 * * * run processes yesterday's interval just after midnight. Set catchup=False if you do not want backfills.
- Airflow defaults to UTC. On a time-zone-aware DAG a cron schedule follows wall-clock time, so a daily 00:00 US/Eastern run moves between 04:00 and 05:00 UTC across daylight saving changes.
The common mistake with this schedule
Writing 9-21 means every hour from 9 to 21, not just those two. Use a comma for exactly two values.
Frequently asked questions
How do I run a Apache Airflow job twice a day at 9am and 9pm?
Use 0 9,21 * * *. At minute 0, during hours 09, 21.
What is the twice a day at 9am and 9pm cron expression in other systems?
Quartz: 0 0 9,21 * * ?; Spring: 0 0 9,21 * * *; Crontab: 0 9,21 * * *. The table on this page lists every dialect.
Which time zone does Apache Airflow use for this schedule?
Airflow defaults to UTC. On a time-zone-aware DAG a cron schedule follows wall-clock time, so a daily 00:00 US/Eastern run moves between 04:00 and 05:00 UTC across daylight saving changes.