From Pulau Senau, lying about 11 miles ENE of Tanjung Tojolawa, the coast is completely exposed to N and NW squalls.
They are prevalent here during the months of October, November, and the first part of December; they may be exceptionally heavy and cause a heavy swell and much sea.

During the Southwest Monsoon, anchorages off this coast, as far W as Pulau Senau, are impracticable because of heavy seas.

When anchoring on the N coast of Pulau Nias, swarms of mosquitoes are blown on board at night with the land breeze, and in view of the prevailing malaria it is advisable to anchor as far as possible offshore.