Marsden Maritime Holdings' earnings this year are expected to be about $1 million less than last year, due to the impact of Cyclone Gabrielle.
In an announcement to the New Zealand stock exchange (NZX) on Tuesday morning, the company downgraded its profit forecast to be in the range of $8m to $8.3m.
The owner of Northport Ltd in Whangarei had underlying earnings of $9.1m in the previous financial year.
The economy in Northland was hit hard by severe flooding and damaging winds brought on by Cyclone Gabrielle which has resulted in reduced log volumes and container numbers through Northport.
It also said the increase in interest rates is likely to create a softening in its profit.
Ahead of its full-year results late next month, the company said it had "a solid result for the first half of the year and gave an interim dividend in line with last year".
The forecast excludes the revaluation of investment property and fair value movements.