Vietnam is expected to see intermittent rainfall over the next 10 days, which together with recent crop-friendly rains may affect harvesting in the second biggest coffee producer, while Indonesia's market was quiet, traders said.

Vietnam's main coffee belt, the Central Highlands, is likely to see a mix of rain and sunny weather in the next 10 days, the National Meteorological and Hydrological Center forecast.

Recent rainfall has prevented beans from turning ripe and ready for harvest, traders said.

"Beans need about two to three weeks of sunny days to be fully grown...It looks like new beans might not be available until the second half of November," said a Ho Chi Minh City-based trader on Thursday.

The country's coffee crop starts from October and ends in September.

In Vietnam, the 5 percent black and broken grade 2 robusta was quoted at a discount of $20-$50 to the London ICE January futures contract, but low stocks and weak demand from importers kept the market dull, traders said.

"Some farmers have started harvesting, but only a few, and they mostly use drying machines...It's not so sunny yet," said Phan Hung Anh, deputy director of Anh Minh Co in Daklak, Vietnam's top coffee-growing province.

The harvest could peak by mid-November, he said.

Farmers in Daklak were offering coffee beans at 42,400-43,000 dong ($1.87-$1.89) per kg , traders said, steady from last week's offer at 42,000-43,000 dong.

In Indonesia, the grade 4 defect 80 robusta beans was being traded at a $40 premium to the January contract in the main coffee growing province of Lampung, a trader said, the same as last week.