@jisaak的答案几乎是Spot On，只是Date组件前面的额外填充空格("Tue Aug42015")会在您尝试解析介于月10号和31号之间的日期时导致错误：

PS C:> [Datetime]::ParseExact('Tue Aug  4 17:05:41 2015', 'ddd MMM  d HH:mm:ss yyyy', $us)

Tuesday, August 04, 2015 5:05:41 PM


PS C:> [Datetime]::ParseExact('Tue Aug 11 17:05:41 2015', 'ddd MMM  d HH:mm:ss yyyy', $us)
Exception calling "ParseExact" with "3" argument(s): "String was not recognized as a valid DateTime."
At line:1 char:1
+ [Datetime]::ParseExact('Tue Aug 11 17:05:41 2015', 'ddd MMM  d HH:mm:ss yyyy', $ ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (:) [], MethodInvocationException
    + FullyQualifiedErrorId : FormatException

最简单的方法是删除输入字符串和格式字符串中的填充空格：

function Parse-CustomDate {
    param(
        [Parameter(Mandatory=$true)]
        [string]$DateString,
        [string]$DateFormat = 'ddd MMM d HH:mm:ss yyyy',
        [cultureinfo]$Culture = $(New-Object System.Globalization.CultureInfo -ArgumentList "en-US")
    )

    # replace double space by a single one
    $DateString = $DateString -replace 's+',' '

    [Datetime]::ParseExact($DateString, $DateFormat, $Culture)
}