Good weather, an extra weekend and high demand for SUVs and pickup trucks contributed to U.S. auto sales having their best month in seven years in May.

Major automakers Chrysler, Nissan and Toyota all reported double-digit sales gains over May 2013. General Motors also surprised analysts with a 13 percent gain in sales despite the recent recalls that they suffered.

Ford gained three percent in sales which was better than expected. The only major automaker to have sales decrease was Volkswagen. VW sales were down 15 percent.

May is normally a good month for auto sales. This year, May had five weekends and many of the automakers offered excellent Memorial Day sales. Automakers said the last week of May was particularly strong for them.

With a cold and snowy January and February leading to weak sales numbers in those two months, analysts predicted May to rebound and for sales to rise seven or eight percent.

"We're still recovering from the low first-quarter numbers that we saw," said Jeff Schuster, executive vice president of forecasting for LMC Automotive, an industry consulting firm. "It's the continued recovery in the summer selling season, kind of everything aligning in the month of May." 

Even without hefty discounts, sales were strong in May, Schuster noted. Car buying website TrueCar.com estimated that May 2013's incentives were about the same as this May's. They were up four percent from April and averaged $2,677 per vehicle. The best incentives in May were from Hyundai, Kia and Honda, TrueCar added. The least amount of incentives in May came from Chrysler, GM and Nissan.

GM said May was its best month since August 2008. Two SUVs, the Buick Encore and the GMC Yukon more than doubled in sales. Additionally, the new Chevrolet Corvette was a big hit.

Customers especially flocked to Nissan. Sales of Nissan vehicles increased 19 percent since last May as customers purchased the small Sentra sedan and Rogue SUV.

Ford was pleased with record sales of the Fusion sedan and Escape SUV, but its truck sales fell.

GM shares are up about 1 percent Tuesday in mid-day trading while Ford is up about 0.6 percent.