LONDON - The euro stood at five-week highs on Thursday before new European Central Bank President Christine Lagarde's first policy meeting, after the Federal Reserve's forecast that it would hold rates through 2020.

The Fed announcement late on Wednesday, which followed its decision to leave rates unchanged, sent the dollar to its weakest since early August.

Traders will scrutinise Lagarde's every word for her take on the ECB's latest stimulus plans, introduced in September, and the bank's economic forecasts. But analysts doubt the ECB meeting will dislodge the euro from the narrow trading range it's been in through 2019.

"The potential for the euro to strengthen is linked more to the improving euro-zone economic data flow rather than any immediate adjustment in ECB policy," MUFG analysts said. "Positive economic surprises are currently running at the highest level since early in 2018".

The euro was up 0.1% at $1.1136 from Wednesday's high of $1.1145, the strongest since early November.

The dollar fell against a basket of currencies, its index falling 0.3% to 97.038, a four-month low.

Investors were also on edge ahead of Sunday's deadline for a new round of U.S. tariffs on China.

Fed Chairman Jerome Powell said the economic outlook for the U.S. was favourable, though the Fed forecasts only moderate and slowing growth through 2020 and 2021.  New economic projections showed 13 of 17 Fed policymakers foresaw no change in interest rates until at least 2021.

The Japanese yen held on to most of its overnight gains at 108.61.

"The Fed has basically given the market confirmation that the three rate cuts we've had recently are not going to be reversed any time in the next year," said Stuart Oakley, global head of flow FX at Nomura in Singapore.

Among those benefiting from the U.S. dollar's slide were the Australian, New Zealand and Hong Kong dollars - the latter rose to its highest since July - as well as some emerging-market currencies.

Sterling rose to its highest since March at $1.3229, amid dollar weakness and confidence Britain's Conservative Party will win a majority in Thursday's election.

A majority would give Prime Minister Boris Johnson's party control of parliament and enable him to lead Britain out of the European Union at the end of January. Anything short of that could prompt a slide in the British currency.

Sterling/dollar overnight implied volatility has soared to its highest since the 2016 Brexit referendum.

Voting ends at 2200 GMT, with exit polls and early results due after that. Traders expect an outcome as early as 0300 GMT on Friday.

(Reporting by Tommy Reggiori Wilkes, additional reporting by Tom Westbrook in Singapore; editing by Larry King) ((thomas.wilkes@thomsonreuters.com))