GitHub Actions Cron Schedule:
UTC, 5-Min Limit & 3 More Gotchas

Unlike Linux cron (which respects the server timezone and supports CRON_TZ), GitHub Actions has no timezone configuration for schedule triggers. The cron: value is always interpreted as UTC.

If you want a job to run at 9am London time, remember London is UTC+0 in winter and UTC+1 in summer (BST). That means '0 9 * * *' in winter and '0 8 * * *' in summer — or accept that local wall-clock time drifts by an hour during DST changes.

Workaround: Handle timezone in the workflow step

steps:
  - name: Run only if it's 9am in London
    run: |
            # Check current London time inside the step
      LONDON_HOUR=$(TZ='Europe/London' date +%H)
      if [ "$LONDON_HOUR" -eq 9 ]; then
        echo "Running at 9am London"
        ./run-task.sh
      fi

This is inelegant but it's the most DST-safe approach if local time matters to you.

GitHub enforces a minimum interval of 5 minutes on scheduled workflows. An expression like * * * * * (every minute) or */2 * * * * (every 2 minutes) will not trigger more frequently — GitHub will simply not run it at the expected cadence, sometimes skipping runs entirely.

# ❌ This will NOT run every minute as expected
- cron: '* * * * *'

# ❌ This will NOT run every 2 minutes as expected
- cron: '*/2 * * * *'

# ✅ This is the minimum that reliably works
- cron: '*/5 * * * *'

If you need sub-5-minute scheduling, use an external service or trigger the workflow via the GitHub API from your own infrastructure.

GitHub's documentation explicitly states that scheduled workflows may be delayed during periods of high load on GitHub's infrastructure. In practice, delays of 5 to 30 minutes are common at peak hours (especially around :00 and :30 past the hour when everyone's jobs are set to run).

This means GitHub Actions cron is not appropriate for time-sensitive tasks. If your job must fire within 60 seconds of the scheduled time, use a dedicated cron service (Linux cron, AWS EventBridge, Google Cloud Scheduler) and trigger the workflow via the GitHub API.

Triggering a workflow via API (reliable alternative)

# Add workflow_dispatch to your workflow file
on:
  schedule:
    - cron: '0 9 * * 1-5'
  workflow_dispatch:  # Allows manual + API triggering

# Then trigger it precisely from your own cron server
curl -X POST \
  -H "Authorization: Bearer $GITHUB_TOKEN" \
  -H "Accept: application/vnd.github+json" \
  https://api.github.com/repos/OWNER/REPO/actions/workflows/WORKFLOW_ID/dispatches \
  -d '{"ref":"main"}'

If a repository has had no commits, pull requests, or other activity for 60 days, GitHub will automatically disable its scheduled workflows. You'll receive an email notification, but if you miss it, your jobs simply stop running with no other warning.

To re-enable them, go to the Actions tab in your repository and click "Enable" on the disabled workflow.

Workaround: Keep the repo active

# Add this step to your scheduled workflow to create a commit
# that keeps the repo active
steps:
  - uses: actions/checkout@v4
  - name: Keep repo active
    run: |
      git config user.email "action@github.com"
      git config user.name "GitHub Action"
      git commit --allow-empty -m "chore: scheduled run $(date -u)"
      git push

This is a standard cron behaviour that surprises people in every context, but it's especially painful in GitHub Actions because you can't easily test it. If you specify a non-wildcard value for both day-of-month and day-of-week, the job fires when either condition is true.

# ❌ Intended: "the first Friday of every month"
# ✅ Actual: "the 1st of every month" OR "every Friday"
- cron: '0 9 1 * 5'

# ✅ To get "first Friday of the month", check inside the workflow step

Correct approach for "first Friday of the month"

on:
  schedule:
        # Run every Friday at 9am UTC
    - cron: '0 9 * * 5'

jobs:
  first-friday-only:
    runs-on: ubuntu-latest
    steps:
      - name: Check if first Friday
        run: |
                    # Only proceed if the day of month is 1-7 (first week)
          DAY=$(date +%d)
          if [ "$DAY" -gt 7 ]; then
            echo "Not the first Friday — skipping"
            exit 0
          fi
          echo "First Friday confirmed — running task"
          ./monthly-task.sh