The coverline will appear on your chart if these 3 qualifications are met:
- Inputted temperatures for 9 consecutive days
- Had a temporal shift that lasted for a minimum of 3 days
- A pattern of temperature for 3 days that appears higher than the previous 6 days.
To learn more about coverlines, check out this article from our community : https://glowing.com/community/topic/1333761/determining-the-coverline.
Unfortunately at the moment, users cannot draw a coverline on their own.