Toggle Dark/Light Mode in Windows 10 automatically by time of day (without modifying or changing theme!)

Question

Nowadays most devices allow for an automatic toggle of Dark/Light mode, however Windows 10 doesn't seem to have such a feature. Is there a way to accomplish this? Using the Task Scheduler for example?

There seem to be many examples on how to change the windows "theme" programmatically, but not the light/dark mode toggle (which can be independently set for "windows mode" or for "app mode" in Settings/Colors).

Answer 1

Yes, there is!

It can be a bit tricky to pull off seamesly, but it can be done with the following steps:

Open Task Scheduler and create a new task with the following settings:

General

• "Run whether user is logged in or not" is required so that a powershell window doesn't flash every time this runs.

• "Do not Store Password" check since it's an offline script

• "Run with highest priviledges" just to be sure nothing interrupts it (optional)

Triggers

• Add one trigger for "On workstation unlock"
• Add one trigger to repeat every hour

Actions

• Add an Action with Program=Powershell and Arguments=$time=(Get-Date).TimeOfDay.Hours; if($time -gt 8 -and $time -lt 19){"Setting Light theme..";Set-ItemProperty -Path HKCU:\SOFTWARE\Microsoft\Windows\CurrentVersion\Themes\Personalize -Name AppsUseLightTheme -Value 1 -Type Dword -Force; Set-ItemProperty -Path HKCU:\SOFTWARE\Microsoft\Windows\CurrentVersion\Themes\Personalize -Name SystemUsesLightTheme -Value 1 -Type Dword -Force} else {"Setting Dark theme..."; Set-ItemProperty -Path HKCU:\SOFTWARE\Microsoft\Windows\CurrentVersion\Themes\Personalize -Name AppsUseLightTheme -Value 0 -Type Dword -Force; Set-ItemProperty -Path HKCU:\SOFTWARE\Microsoft\Windows\CurrentVersion\Themes\Personalize -Name SystemUsesLightTheme -Value 0 -Type Dword -Force;}

That PS script seems like a lot packed into a single line, but that's just so we can paste it in that "arguments" diaglog in the Action. So let's break it down a bit to see what it does:

# Set current time in a variable
$time=(Get-Date).TimeOfDay.Hours; 
# if later than 8am and earlier than 7pm, use light mode
if($time -gt 8 -and $time -lt 19){ 
    "Setting Light theme.."; # output in case we let a window be opened
    # set "app" system mode to "light"
    Set-ItemProperty -Path HKCU:\SOFTWARE\Microsoft\Windows\CurrentVersion\Themes\Personalize -Name AppsUseLightTheme -Value 1 -Type Dword -Force; 
    # set "OS" system mode to "light"
    Set-ItemProperty -Path HKCU:\SOFTWARE\Microsoft\Windows\CurrentVersion\Themes\Personalize -Name SystemUsesLightTheme -Value 1 -Type Dword -Force; 
} else {
    "Setting Dark theme..."; # output in case we let a window be opened
    # set "app" system mode to "dark"
    Set-ItemProperty -Path HKCU:\SOFTWARE\Microsoft\Windows\CurrentVersion\Themes\Personalize -Name AppsUseLightTheme -Value 0 -Type Dword -Force; 
    # set "OS" system mode to "dark"
    Set-ItemProperty -Path HKCU:\SOFTWARE\Microsoft\Windows\CurrentVersion\Themes\Personalize -Name SystemUsesLightTheme -Value 0 -Type Dword -Force; 
}

Update:

Although neatly-compact, maintaining code in a single line can be a hassle, so if you prefer to keep your PS script in a .ps1 file, you can excecute it from there simply by putting Powershell.exe (or pwsh.exe) in the Program box, and then -file C:\yourscript.ps1 as argument):