NEW YORK--Oil futures climbed to a 14-week high Monday as investors looked toward signs of stronger demand in the second half of the year.

Light, sweet crude for July delivery settled up $1.75, or 1.7%, at $104.41 a barrel on the New York Mercantile Exchange, the highest settlement price since March 3.

Brent crude on the ICE futures exchange rose $1.38, or 1.3%, to $109.99 a barrel.

The widely traded price gap between the two contracts fell to $5.58 a barrel, its narrowest level since April 15.

Ahead of the Organization of Petroleum Exporting Countries' meeting in Vienna on Wednesday, market watchers questioned whether members of the oil-producers' cartel would increase production to meet expected higher demand later this year.

OPEC produces one of every three barrels of oil consumed daily in the world. The cartel has maintained its current production ceiling of 30 million barrels a day since 2011 and is expected to leave the ceiling unchanged.

However, analysts expect demand for OPEC's oil to be higher in the second half of this year, with the International Energy Agency predicting it will average 30.7 million barrels a day.

Saudi Arabia expects to increase its output, an oil official with the Kingdom said in Vienna on Monday.

But even with higher Saudi production, "I think (the supply-and-demand balance) will still be pretty tight in the second half" of 2014, said Andy Lebow, senior vice president for energy at Jefferies Bache LLC.

Prices also got a boost from recent macroeconomic data indicating that oil demand could rise in the top three oil-consuming nations: the U.S., China and Japan.

The U.S. added slightly more new jobs than expected in May, the government said Friday.

Chinese crude-oil imports rose 8.9% in May compared to a year ago, according to data released Sunday.

And on Monday, the Japanese government raised its gross domestic product reading for the first quarter of the year to an annualized growth rate of 6.7%, exceeding economists' expectations.

"We may have gotten some speculative buying coming in today on the macro data," Mr. Lebow said.

Front-month July reformulated gasoline blendstock, or RBOB, settled up 4.58 cents, or 1.6%, at $2.9848 a gallon. July diesel rose 2 cents, or 0.7%, to $2.8912 a gallon.