By Melanie Burton
MELBOURNE, Oct 15 (Reuters) - An El Nino weather pattern that is expected to be the strongest in nearly 20 years looks set to hit copper mining over the coming months, but should boost production of bauxite, nickel ore and tin in 2016, industry sources said.
The weather phenomenon leads to hotter sea temperatures in the west Pacific Ocean, which means more rain falls on South America and less in Australia and South East Asia.
A shorter monsoon in Indonesia the Philippines and Malaysia can help miners produce more tin, nickel and bauxite - key materials for the construction, transport and electronics industries.
"Dry weather is a good time to mine, because most of our production is off-shore and also the weather is calmer," Agung Nugroho, corporate secretary at Indonesian tin producer, PT Timah told Reuters.
Indonesia is the world's biggest exporter of the metal, which is seen in a balanced market this year. Production often dips due to heavy rains in December and January.
In Malaysia, a shorter rainy season could boost bauxite production by anything between 10-20 percent, a geologist at a miner in Kuantan, in Pahang state, said. Malaysia is the second-biggest supplier to China of the ore used to make aluminium.
Philippine nickel miners are also betting drier weather will let them mine until year end, while Australia's iron ore and coal exports are less likely to be disrupted by cyclones in the upcoming cyclone season.
While a strong El Nino helps the minig of some metals, the opposite is true for copper as too little rain in Asia and too much in South America crimps supplies.
Ok Tedi Mining's copper mine in Papua New Guinea has already been forced to shut after a drought cut off river transit links, while Freeport-McMoRan blamed El Nino as it cut its 2015 forecast for copper concentrate sales from Indonesia as less water impacted its milling operations.
Meanwhile, mining operations in Chile, the world's top producer, remain vulnerable to disruption after heavy rains this year cut power and flooded mine shafts.
Some miners expect less impact. Dr Fred Hess, managing director of PanAust, which is preparing a feasibility study for the giant Frieda River copper and gold lode in Papua New Guinea, told Reuters that the company has assessed the impact on El Nino this year on water levels it would use to transport its ore.
"We think largely it won't have any impact on our operations when we get Frieda River up and running, so that's been quite useful, being able to see the river conditions during one of these extreme events."
(Additional reporting by Emily Chow in Kuala Lumpur, Mitra Taj in Lima Michael Taylor in Jakarta; Editing by Gavin Maguire and Ed Davies)