Unexpected delay in scheduled GitHub Actions workflows using cron

[SssoDev]

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Hello GitHub Support Team,

I'm currently using GitHub Actions to schedule a workflow using the cron syntax, and I’ve been encountering some unexpected behavior related to execution time.

For example, when I set:

schedule:
- cron: "0 21 * * *"

...the job runs around 6:30 AM KST the next day. Similarly, when I set:

schedule:
- cron: "0 9 * * *"

...the job runs around 6:30 PM KST.

I also tested:

schedule:
- cron: "0 0 * * *"

...expecting it to run at 9 AM KST (since GitHub Actions use UTC), but the job ran around noon instead.

There also appears to be a consistent delay of about 30 minutes on each run, which makes it hard to determine the precise execution time.

I'm wondering:

• Are there known delays with cron jobs on GitHub Actions?
• Could workflows from other users affect when mine is executed?
• Is there any way to ensure more accurate timing?

Any insight or advice would be greatly appreciated.
Thank you in advance for your help!

Best regards,
SssoDev

[github-actions[bot]]

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[sefinek]

Hello!

1. Hm, I just checked how it looks on my end. I have an action in one repository scheduled with 0 0 * * *. The cron job ran on April 10, 2025, at 2:29 AM (GMT+2), so with a 29-minute delay. Based on UTC, it should've triggered at 00:00 UTC, which corresponds to 2:00 AM local time in GMT+2 (daylight saving). Just to clarify, I live in the Europe/Warsaw time zone.

2. Other users’ workflows don’t directly impact your jobs, but GitHub uses a shared pool of runners (unless you're on self-hosted), so resource availability at a given moment can affect when your job actually starts.

3. If precision is crucial, it’s worth considering self-hosted runners – you get full control over the environment and avoid GitHub’s queueing. Alternatively, you can schedule the job ahead of time and use a sleep to align it with the exact hour.

[adambirds]

Self hosted runners don't stop the delay, github isn't even bothering to trigger my scheduled actions

[sefinek]

Strange, I've never had any issues like that with runners. Make sure that both the server and the workstation have their time properly synchronized.

E.g.:

dpkg-reconfigure tzdata

[braboobssiere]

• Is there any way to ensure more accurate timing?

i give up and use third party cron instead, more reliable than github built-in schedule (the delay at worst is less than 1 min. from schedule time) https://cron-job.org/en/

[adambirds]

Yeah if it doesn't get better I'm just gonna switch to cron jobs on my Kubernetes cluster tbh!

[psyfox]

Same problem here.

I'm almost giving up on using GitHub Actions in our Enterprise account...
Taking over 30 minutes to start a simple cron job that's supposed to run every 5 minutes on a self-hosted runner...
That's just surreal.

[carrot-liang]

I am triggering the action by a self hosted cron api request

[psyfox]

I am triggering the action by a self hosted cron api request

Seemed to be the best fast-win solution to me so far.
Thanks.