CHICAGO (AP) — McDonald's lesson from July: If you want to start selling cold, fruity drinks, pick one of the hottest months in US history.

The fast-food giant posted its biggest monthly increase in more than a year in an important US sales figure as US as the fast-food chain's new fruit smoothies and ice-cold frappes got a warm reception from customers.

The increase shows just how much the behemoth is outpacing its competitors as customers keep flocking to the world's largest hamburger chain while competitors post anaemic US sales. Shares touched an all-time high yesterday morning. "They were pretty impressive results," said Morningstar restaurant analyst R.J. Hottovy. "It just shows that the smoothies product has been a big win for the company and a big hit among consumers. They did well with the timing of the product."

July sales at restaurants open at least 13 months climbed 5.7 percent — the biggest monthly increase since it recorded a 6.1 percent gain in April 2009. At the same time, the National Weather Service said the month was one of the the hottest on record nationwide, shatterring records in many East Coast cities.

Overall, McDonald's Corp. said the sales measure rose seven percent around the globe and outpaced expectations.