Why isn't this implemented yet? gitlab is already having this functionality afaik

Thanks for the feedback @cj81499. I certainly agree that time zones and scheduling is tricky, so I'll make sure that this is on the backlog.

Another really useful feature would be to be able to add random jitter like cron supports because we can run into ratelimits when we have multiple actions running at the same time.

As a super hacky workaround, you can schedule your workflow to run at BOTH standard and daylight times, and then use a bash script to filter out the undesirable runs. This means you'll have 2 runs for every schedule date, but only one of them will execute past the Test schedule step.

Something like this should work:

on:
  schedule:                             
    - cron: "00 18,19 * * TUE"    # Run every tuesday at 12:00 noon MDT (GMT-6) and MST (GMT-7)

env:
  TZ: "America/Edmonton"
  LOCAL_TIME: "12:00"
  
jobs:
  test-date:
    runs-on: ubuntu-latest
    steps:
      - name: Test schedule
        if: github.event_name == 'schedule'
        run: |
          now=$(date +%s)
          local_time=$(date -d "$LOCAL_TIME" +%s)

          if [[ $now -gt $local_time && $now -lt "$((local_time + 3600))" ]]; then
              echo "🌞 Passed daylight savings time check!"
          else    
              echo "⏱ Waiting until $LOCAL_TIME."
              exit 1
          fi

I've created a Workaround like @bcowdery, but mine won't fail the run:

on:
  schedule:
    - cron: '5 16,17 * * *'

jobs:
  check-run:
    runs-on: ubuntu-latest
    outputs:
      run: ${{ steps.check_local_time.outputs.run }}
    steps:
      - name: Check local time
        id: check_local_time
        env: 
          TRIGGER: ${{ github.event_name }}
        run: |
          echo "Trigger: ${TRIGGER}"
          if [[ ${TRIGGER} == 'schedule' ]]; then
            echo "Checking daylight saving time"
            if [ $(date --date='TZ="Europe/Berlin" now' +%H) -eq '18' ]; then 
              echo 'Time to run!'
              echo "run=True" >> "$GITHUB_OUTPUT"
            else
              echo "It's not 18:05 local time in Europe/Berlin. Waiting for next execution..."
              echo "run=False" >> "$GITHUB_OUTPUT"
            fi
          else
            echo 'Trigger is not cron, ommiting time check!'
            echo "run=True" >> "$GITHUB_OUTPUT"
          fi
  
  my-job:
    runs-on: ubuntu-latest
    if: needs.check-run.outputs.run == 'True'
    needs: check-run

Still, I would love to not use this workaround, but perhaps this is useful for anybody.

Please do not comment "waiting...", "+1", "need this", etc.

It adds nothing to the conversation and spams our inboxes. Instead, leave a thumbs up or upvote to show your interest in this feature.

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Reading the comments here, it is unclear to me whether or not the code responsible for accommodating timezone is public or not. If it is, can someone share which repo and code the community can work with to add this feature?

We are currently having a look at this to see what we can do :) hopefully this is something we can get moving very soon