* EUR/USD extends gains, hits highest since January 2015

* Euro boosted after ECB's Draghi refrains from talking it down (Updates prices, adds details)

By Shinichi Saoshiro

TOKYO, Aug 28 (Reuters) - The euro extended gains to a 2-1/2-year high against the dollar on Monday after the European Central Bank president did not try to talk down the currency and as markets worried about the impact of Tropical Storm Harvey on the U.S. economy.

The euro was 0.15 percent higher at $1.1934 after rising to $1.1966, its highest since January 2015.

The common currency had already surged about 1 percent on Friday after ECB President Mario Draghi spoke at Jackson Hole on subjects such as global trade but did not touch upon the euro's recent strength.

The euro had already gained an earlier lift against the dollar after Federal Reserve Chair Janet Yellen made no reference to U.S. monetary policy at Jackson Hole.

"I don't think expectations were that high in the market that Draghi would talk down the euro at Jackson Hole. Even if he had done so, the euro likely would have risen anyway," said Masafumi Yamamoto, chief forex strategist at Mizuho Securities.

"A strong euro cannot be a source of complaint for a region like the euro zone which is blessed with a large current account surplus, a steady economy and is not threatened by deflation. It was thus an opportunity for speculators to buy the euro without much concern."

With much of the immediate focus on the euro after Jackson Hole, the dollar did not fare as badly against the Japanese yen.

The greenback was down 0.1 percent at 109.295 yen after dipping to 109.110 on Friday. It remained clear of the four-month low of 108.605 touched on Aug. 18.

The Swiss franc stood near a one-month high of 0.9539 franc per dollar touched earlier in the session. The franc had surged 0.9 percent on Friday.

The pound was steady at $1.2897 after briefly touching a 13-day peak of $1.2946.

The dollar index fell 0.3 percent against a basket of six major currencies, adding to Friday's losses and plumbing 92.372, its lowest since early May 2016.

"Markets (were) disappointed on the Yellen speech and they sold the dollar and pushed bond yields down," said Imre Speizer, Westpac markets strategist.

He said Harvey would likely further weigh on the U.S. dollar since it's "a major negative weather event "and "obviously bad for the economy."

Catastrophic flooding inundated Houston on Sunday. The Gulf Coast is home to about nearly half of the nation's refining capacity.

The Australian dollar was a shade higher at $0.7938 and the New Zealand dollar rose 0.1 percent to $0.7245. (Reporting by Shinichi Saoshiro; Additional reporting by Ana Costa; Editing by Eric Meijer and Kim Coghill)