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Getting time zone information in PowerShell is an exercise in simplicity. This single command:

[TimeZoneInfo]::Local

… yields about as much information as you’d generally care to know about the current system time zone.

Sample results:

Id                         : Mountain Standard Time
DisplayName                : (UTC-07:00) Mountain Time (US & Canada)
StandardName               : Mountain Standard Time
DaylightName               : Mountain Daylight Time
BaseUtcOffset              : -07:00:00
SupportsDaylightSavingTime : True

Setting the current time zone, unfortunately, isn’t quite as easy or intuitive. This is something I needed to do a while back for my desktop imaging process. Although the runtime portion of the Microsoft Deployment Tools (MDT) are largely built on a VBScript foundation, most of my deployment scripts are PowerShell-based, so I came up with a simple Posh function for setting the system time zone that works for both Windows XP and Windows 7.

There are a number of crazy ways to set time zone information, but rather than delving into methods that directly modify the registry and such, I decided upon documented, supported ways to change the current time zone:

function Set-TimeZone {
 
	param(
		[parameter(Mandatory=$true)]
		[string]$TimeZone
	)
 
	$osVersion = (Get-Item "HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion").GetValue("CurrentVersion")
	$proc = New-Object System.Diagnostics.Process
	$proc.StartInfo.WindowStyle = "Hidden"
 
	if ($osVersion -ge 6.0)
	{
		# OS is newer than XP
		$proc.StartInfo.FileName = "tzutil.exe"
		$proc.StartInfo.Arguments = "/s `"$TimeZone`""
	}
	else
	{
		# XP or earlier
		$proc.StartInfo.FileName = $env:comspec
		$proc.StartInfo.Arguments = "/c start /min control.exe TIMEDATE.CPL,,/z $TimeZone"
	}
 
	$proc.Start() | Out-Null
 
}

You can call this function using the friendly time zone name associated with the zone you want. For example,

Set-TimeZone "Pacific Standard Time"
Set-TimeZone "North Asia East Standard Time"
Set-TimeZone "GMT Standard Time"

… and so on.

Note that the function uses the .NET Process class to execute the necessary commands. The Windows 7 tzutil method doesn’t need this, but the control.exe command used for XP and earlier won’t work with the Start-Process cmdlet, so I went with the lowest common denominator.