* Natural gas sinks to lowest since Sept. 26
* Drop in euro weighs on copper
* Arabica hits fresh 4-1/2 year low on abundant supplies
By Marina Lopes
NEW YORK, Nov 4 (Reuters) - Natural gas and base metals led a gentle pull-back in generally lackluster commodity markets on Monday, dragging a key index to a 16-month low for a second day.
Above-normal temperature forecasts in the majority of the United States curbed heating demand, pulling natural gas to its lowest in almost six weeks, while a shaky euro weighed on metals. Oil and gold prices were little changed.
Upbeat manufacturing data in Europe rescued the euro from a near seven-week low against the dollar earlier in the session, while sluggish consumer demands for a wide range of capital goods in the United States raised expectations the Federal Reserve will prolong its economic stimulus.
Comments from a senior Fed official in Sydney that the central bank should keep its monetary stimulus, bolstered expectations of a prolonged stimulus and edged the dollar up.
The Thomson Reuters/Core Commodity CRB index closed down almost half a percent, with losses in 14 of the 19 components. It was the lowest close since July 2012, with the index having fallen 5 percent in less than three weeks.
U.S. equities were little changed after a week of record highs, as debates about when the Fed will ease its stimulus policy kept trading volumes at bay. Gold ended little changed at around $1,314 an ounce.
"Gold is still very dependent on economic weakness and extended quantitative easing to prosper at the moment," said Saxo Bank's head of commodity strategy Ole Hansen.
U.S. natural gas futures slid almost 2 percent on warmer weather forecasts, keeping the nearby contract well below both the 100-day and 200-day moving averages, a bearish sign.
"Natural gas futures have flushed further to the downside as the temperature forecasts continued to trend somewhat warmer through the weekend, removing some heating demand and likely postponing the start of seasonal storage withdrawals," said Citi Futures energy analyst Tim Evans.
Front-month December natural gas futures on the New York Mercantile Exchange settled down 7 cents at $3.45 per million British thermal units, or almost 2 percent.
Copper fell for a third consecutive session due to a drop in the euro, but remained firmly within a range that has persisted for months on uncertainty about the outlook for demand from top consumer China.
Benchmark copper on the London Metal Exchange closed at $7,149 a tonne, down from a last bid of $7,240 on Friday.
Copper has traded in a $7,000-$7,420 range since early August partly due to uncertainty about real demand growth from China.
Bonded stocks in China are climbing, while premiums have begun to soften. Citi has estimated that bonded copper stocks have increased to around 450,000 tonnes from lows of 300,000 tonnes a month or two ago, while stocks have also built up in domestic non-exchange warehouses.
ICE arabica coffee futures sank to their lowest level since March 2009, pressured by abundant global supplies and speculator selling, while robusta coffee in London edged down in mixed trading and hovered near Friday's price, the lowest in more than three years.
December arabica coffee on ICE Futures U.S. sank 1.85 cents, or 1.8 percent, to settle at $1.0370 per lb, just above the day's 4-1/2 year low of $1.0335.
ICE raw sugar futures gained, recovering from a one-month low on currency and technical support.
Cocoa futures on ICE hit a four-week trough due to harvest pressure from West Africa, the world's top growing region.