Coffee prices were rallying Monday as dry weather in Brazil left traders concerned that the current crop would deteriorate.

Benchmark futures contracts were rising 4.2% at $1.34 a pound in recent action. "Coffee is in its bloom stage now, and it needs rain," says Jerod Leman, a grains broker at Wellington Commodities in Carmel, Ind.

Without the rain, both the quantity and quality of the crop will be adversely affected, he says. That worry only adds to supply concerns in an increasingly tight global coffee market.

"Supply is only barely meeting demand," Leman says.

Weather-related anxiety was also prompting another rally in wheat prices, with benchmark contracts recently trading for $9.51 a bushel, around record levels. A lack of precipitation in Australia amid generally low inventories for the grain prompted the rise.

Shares of agribusiness firm Bunge ( BG) were up 0.3% at about $108.

Elsewhere, precious metals prices were slipping slightly, with gold down 10 cents at $749.90 an ounce and silver off 12 cents at $13.81 an ounce in recent New York futures market action.

Copper prices were rising 2 cents at $3.66 a pound.

Amir Arif, an analyst at Freidman Billings Ramsey, says he believes aluminum giant Alcoa ( AA) will miss the consensus estimates when the firm reports its quarterly earnings next week.

Shares of Alcoa were slipping 0.4% in morning activity.

Meanwhile, diversified miners BHP ( BHP) and Rio Tinto ( RTP) were moving ahead by 1.8% and 1.6%, respectively.