Graded and ungraded adjectives
Pattern 20: how ADJ it v-link that
The adjective follows how and is followed by introductory it, a link verb, and a that-clause. The that-clause refers to the fact or event that is being commented on.
Over the past year, I have discovered how important it is that we as parents choose our child's school very carefully.
How splendid it is that you are here.
Sometimes the that-clause comes directly after the adjective. This pattern is how ADJ that.
How wonderful that overseas visitors are so drawn to the great heritage of France.