How do I change celsius to fahrenheit temperature in today summary in notification center?

I believe the settings there are based on the settings you have for the system as a whole, so open up System Preferences, go to Language & Region, and make sure the region is set to where you live, if where you live doesn't use the metric system. I'm in the United States, which uses Fahrenheit, so that's how the Today summary appears to me in the Notifications Center.

Open up the panel, go to the weather line and slide your cursor to the right until a circled i appears. Click that and where it shows add, change on the right side. Then click Done.

In the following image obtained from the today panel on El Capitan, the °C / °F indicators are selectable.

On the iPad, the temperature display setting is stored in the Clock app of all places! (I found this solution in another thread). This was driving me crazy. This affects the temperature units for the Today Summary in Notification Center.

As I said, the temperature you see in the Today summary, not the weather widget, comes from whatever region you have set your system to. I'm in the United States, so it shows temperatures in Fahrenheit. If I lived in the UK, it would show in degrees Celsius.

On the Mac, click on the i for info. Click on ° F

Select Done

Do you have any custom settings under Language & Region? For example, when you click on the Advanced button, do you have "Measurement units" set to US? If I change mine to UK, the weather in my Today summary shows in degrees Celsius.

That's not the Today summary, that's the Weather widget. They're two separate things.

I had this problem as well. I finally figured out a solution.

Go to System Preferences/Language & Region/

then change the Region Popup to "United States (Computer)". That seemed to do it.

Strangely, when I first tried changing Region to somewhere other than "United States" then back to "United States" it stayed in Celsius but as soon as I changed it to "United States (Computer)" it switched to Fahrenheit.

This has been driving me crazy for months! (It's the little things in life that can push you over the edge!)

Thank you so much for this solution.