Is AnuCal a diary?

Not exactly. You can use it to remember your year, but it is lighter than a diary. A small note, emoji, color, or anchor can be enough.

For a small diary, add a sun or rain stamp to record the weather. Open that stamp and write something good about the day in its description, such as a nice walk or a chat with a friend. You can use the same notes, formatting and checklists as any other event, and expand the panel on desktop if you want more room.