Mr Hall, who has spent a decade in the role, made the announcement in the school newsletter yesterday.
He said it was a "carefully considered decision".
He believed it was a good time to transition to the next principal.
"The Phase 2 expansion [of the school] will be complete, the school is performing well, and is financially sound and well-supported, with a strong leadership team — WHS is well-placed to continue to grow and move forward successfully."
School board chairman Charlie Phillips said while there would be time at the end of the year to acknowledge Mr Hall’s "immense contribution" to the school, he thanked him for his "outstanding commitment in leading the transformation of WHS into a high-performing New Zealand secondary school".
"On behalf of the school, I would like to pass on a sincere and genuine thank you to him."
