Why doesn't Apple 6splus display its own weather?

The system of the iphone used should be ios6 or below, while the iphone 6s uses ios9. After using ios7, the weather notification is turned off by default, and the forecast for the next five days will not be displayed, only the weather of the day will be displayed.

Do not display the weather at this location; Check settings, privacy, location services, and set "Weather" to "Always".

IOS system has no desktop plug-in, so it can't display the weather forecast on the desktop. Android can.

The most convenient way for iPhone to display the weather forecast is to add weather plug-in to the notification bar, so that you can see the weather after the drop-down menu, which is what I use at present.