McDonald's Corp. posted its biggest monthly increase of a key U.S. sales figure in two years on Monday, saying its new fruit smoothies and frappes were a hit with customers during a hot and steamy July.

In the U.S., sales at restaurants open at least 13 months climbed 5.7 percent — its biggest monthly increase since it a 6.7 percent gain in July 2008.

Overall, the measure rose 7 percent around the globe. It climbed 5.3 percent in Europe and 10.1 percent in the rest of the world, the world's largest hamburger chain said in a statement on Monday.

The figure is considered an important gauge of a restaurant chain's performance because it excludes the effects of restaurants that open or close during the year.

McDonald's shares climbed 67 cents to $72.41 in pre-market trading Monday. The company's stock closed Friday at $71.74.

McDonald's is based in the Chicago suburb of Oak Brook, Ill. It has more than 32,000 restaurants around the world in 100 countries. About 14,000 of its locations are in the U.S.