March raw sugar settled up 0.11 cent, or 0.9 percent, at 12.76 cents per lb, after climbing to a fresh Dec. 19 high. This was the contract's third straight positive finish.
Prices were supported by higher oil prices, chart-based buying and the threat of damaging weather in major sugar-producing countries, dealers said.
Oil prices were more than 2 percent higher on demand hopes related to the US-China trade talks. Higher oil prices encourage the increased use of sugarcane for ethanol production in Brazil, a top grower.
In the prior session, sugar rallied 6 percent to improve the technical picture, dealers said, as well as spurring follow-through buying and short-covering.
Open interest on Monday fell by 14,524 lots to 898,917 lots, ICE data show. A drop in open interest alongside a price increase is an indicator of short-covering.
Signs of dry weather in key cane-producing regions of India and Brazil, the world's two largest sugar producers, also supported prices, dealers said.
But momentum remained mostly speculative, dealers said, and higher prices could attract producer selling from India, which has lagged in exporting a large surplus.
March white sugar settled up 60 cents, or 0.2 percent, at $345.40 per tonne.
March arabica coffee settled up 2.3 cents, or 2.2 percent, at $1.0505 per lb after earlier touching $1.0605, its highest since Nov. 30.
Brazil's currency - the real - has firmed over 6 percent against the US dollar since the end of December, lifting coffee prices, dealers said. A stronger real discourages producer selling by diminishing local returns on dollar-traded commodities like coffee and sugar.
Prices also got a boost after breaking above technical levels, dealers said. The market's move above recent highs around the $1.0390 and $1.04 levels triggered additional buying interest, said Rodrigo Costa, director of trading at Comexim USA.
Honduran coffee exports fell more than 15 percent in December due to delays in the harvest, the head of the country's association of coffee exporters said on Monday.
March robusta coffee settled up $14, or 0.9 percent, at $1,556 per tonne.
March New York cocoa settled down $28, or 1.2 percent, at $2,382 per tonne, partly pressured by the stronger dollar.
May London cocoa settled down 13 pounds, or 0.7 percent, at 1,760 pounds a tonne.