WASHINGTON (AP) — The International Monetary Fund says the U.S. economy's stumble at the start of 2015 is dragging down the world's growth prospects.

In a report Thursday, the IMF forecasts 3.3 percent global growth this year, down from the 3.5 percent it predicted in April. The main culprit: The American economy, world's biggest, shrank at a 0.2 percent annual rate from January to March, hurt by nasty weather. The IMF is cutting the outlook for U.S. growth to 2.5 percent in 2015, from April's 3.1 percent. The U.S. economy grew 2.4 percent in 2014.

America's troubles pinched its neighbors. The IMF trimmed Mexico's 2015 growth forecast to 2.4 percent from 3 percent and Canada's to 1.5 percent from 2.2 percent.

The IMF expects global growth to improve to 3.8 percent next year.