Powershell register scheduled task that respects daylight savings time

The scheduled task trigger must be modified to be in local time.

1. Create your trigger as normal

   $trigger = New-ScheduledTaskTrigger -Daily -At 10:15am
   

2. Then edit the trigger's StartBoundary property:

   $trigger.StartBoundary = [DateTime]::Parse($trigger.StartBoundary).ToLocalTime().ToString("s")
   

Explanation: When you create the trigger with New-ScheduledTaskTrigger, the time you specify is converted to UTC time and saved as a string in the trigger's StartBoundary property. On my machine, 10:15am produces a $trigger.StartBoundary of "2017-12-19T15:15:00Z", where the "Z" indicates UTC time. To specify a local time, we need to convert this date back into local time and remove the "Z"; we want "2017-12-19T10:15:00". The snippet above parses the date string, converts it to local time, and formats it in the correct format.

If you need to do this a lot you may find this function helpful:

function Fix-Trigger {
    param( [parameter(ValueFromPipeline)] [CimInstance] $trigger )
    $newTrigger = $trigger.Clone()
    $newTrigger.StartBoundary = [DateTime]::Parse(
        $trigger.StartBoundary).ToLocalTime().ToString("s")
    $newTrigger
}

# Example usage:
$trigger = New-ScheduledTaskTrigger -Daily -At 10:15am | Fix-Trigger

This is all from here.