Windows 8.1 Weather app : Frequently asked questions (FAQ)
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Windows 8.1 how do I change from Celsius to Fahrenheit in Bing weather?
Hi Ellen - it is the first question on that link windows.microsoft.com/.../weather-app-faq
You can customise the units of measurement for temperature based on your personal preference.
1.Swipe up from the bottom of the screen or right-click with your mouse.
2. Tap or click the button marked Change to Celsius or Change to Fahrenheit.