The "Upcoming Alarm" indicator in the notification panel/System UI and in the default weather widget is often incorrect. In the screenshots below, it can be seen that the current time is 11:56, Sep. 4, and the next alarm - according to the clock app - is at 8:30, Sep. 5. However, the indicator in both the widget and the notification panel display (Thu.) 00.30.
At times, the indicator also displays 06:31 for no discernible reason. I'm on the latest EU firmware, (189_0).