Exports of iron ore to China via the Port Hedland terminal rose 5 percent in December from November, underscoring in part a subdued start to the Australian cyclone season, figures released on Tuesday showed.

December shipments to China from Port Hedland, which handles about a fifth of the world’s seaborne trade, increased by 1.57 million tonnes month-on-month to 30.6 million, according to Pilbara Ports Authority.

The increase, in the face of depressed spot iron ore prices linked to a global supply glut and slowing Chinese demand growth, swept total December exports via the port to 37.8 million tonnes, an increase of 7.8 million tonne, or 26 percent rise versus the same month in 2013.

“While the slowdown in China’s apparent steel demand has weighed on sentiment, strong supply growth has been the primary driver of the steady decline,” Morgan Stanley (Xetra: 885836 – news) said in a research note.

So far this year, there has been an absence of cyclones in northwest Australia, which typically close shipping lanes and can force iron ore miners to suspend operations and evacuate staff, curbing supply to ports. The cyclone season officially runs from Nov. 1 to April 30.

A tropical low pressure system this week brought heavy rain to northwest Australia, with a chance of up to 50 percent that it could strengthen into a tropical cyclone by Wednesday.

At this stage, iron ore companies and port operators were keeping an eye on the storm’s movements.

Australia’s biggest producers, Rio Tinto (Xetra: 855018 – news) and BHP Billiton are expected to report record iron ore output in their next quarterly reports Jan 20 and Jan 21 respectively.

Fortescue Metals Group, shipping up to 155 million tonnes annually, is looking to make more incremental increases.

Iron ore was last quoted at $70.80 per tonne. The steelmaking commodity dropped as low as $65.60 a tonne in late December, the lowest since June 2009.