US STOCKS-Wall St climbs as Bernanke spurs bets on low rates

* Fed chairman downbeat on economy, says watching dollar

* Commodity stocks lead broad-based advance as dollar sags

* Dow up 1.5 pct; S&P 500 up 1.8 pct; Nasdaq up 1.7 pct

* For up-to-the-minute market news, click [STXNEWS/US] (Updates to midafternoon, changes byline)

By Ellis Mnyandu

NEW YORK, Nov 16 (Reuters) - U.S. stocks rallied broadly to fresh 13-month highs on Monday after Federal Reserve Chairman Ben Bernanke reinforced expectations that interest rates would stay low to spur growth.

In a speech before the Economic Club of New York, Bernanke said the recovery would not be as robust as previously hoped, and rising unemployment and tight bank lending were significant headwinds.

He repeated that the Fed was likely to keep interest rates exceptionally low for "an extended period," a pledge that drove the U.S. dollar lower and drove investors to snap up shares of natural resource companies as prices of global commodities -- from gold to wheat -- shot higher.

The S&P materials .GSPM and energy .GSPE indexes each climbed nearly 3 percent. Individual stock standouts included Exxon Mobil Corp (XOM.N), up 2.7 percent to $74.43, amid higher crude oil prices.

"The overriding message from Bernanke is that interest rates will stay low and remain low for the near to medium term. It seems that the market likes that," said Dennis Cajigas, senior market strategist at Lind-Waldock, a retail brokerage firm, in Chicago.

"Investors essentially are borrowing against low rates in the dollar and putting that money in areas that they feel will react well against inflation, such as crude oil, energy, gold, commodities, stocks because the expected return should be higher over time."

The Dow Jones industrial average .DJI climbed 158.56 points, or 1.54 percent, to 10,429.03. The Standard & Poor's 500 Index .SPX leapt 19.82 points, or 1.81 percent, to 1,113.30. The Nasdaq Composite Index .IXIC gained 37.00 points, or 1.71 percent, to 2,204.88.

The benchmark S&P 500 is now up 64.5 percent since the 12-year closing low of March 9 and on Monday it was on track to close above the psychologically important 1,100 level for the first time since October 2008.

Shares of Caterpillar Inc (CAT.N), whose fortunes are closely tied to the commodities industries including mining, shot up 3.4 percent to $60.80, making the heavy equipment maker the biggest boost for the Dow.

Shares of AK Steel Holding Corp (AKS.N) jumped 8.22 percent to $18.81, while gold miner Newmont Mining (NEM.N) added 3.4 percent to $52.73. The gold bugs index .HUI jumped 4 percent after COMEX December gold GCZ9 hit a record above $1,140 an ounce.