Memorial Day weekend is the unofficial start of summer and traditionally the beginning of a quieter period for equities. But recent gains and increased optimism in a second-half recovery mean that just because school's out for summer, the stock market most certainly is not.

"The old adage 'Sell in May and Go Away' is a very dangerous proposition this year," says Brett D'Arcy, director of investment and research at CBIZ Financial Solutions (CBZ) . "Given the recent trajectory of the market and the timing of the stimulus funds into the economy, I think the summer could turn out to be a very profitable time for investors."

True, there is something to the Sell-in-May saying: Plexus Asset Management crunched the average monthly total return of the S&P 500 from January 1950 to April 2009. Sure enough, only September and October produced lower results than June, July or August.

See 5 stocks set to shine this summer

There are other caveats with seasonal investing, the most salient being that the market knows that summer comes every year. As such, expected gains in sales and earnings tend to get baked into share prices months in advance.

But that doesn't mean there aren't some solid summer stocks out there that could offer upside surprise by autumn, thanks to larger macro trends or company-specific strengths. From energy to lawn care to summer blockbusters, here, then, is a look at five stocks for summer.

The maker of Monster energy drink has been one of the best-performing stocks of the last decade and now it looks set to have a monster summer, too. "They're taking market share in the one category in the beverage space that is actually still growing -- energy drinks," says Damian Witkowski, an analyst with Gabelli & Co., who rates shares at Buy. Hansen (HANS) is rolling out two new products -- Hammer X-Presso Monster and Monster Import -- just in time for the all-important summer beverage season. Moreover, the company is expanding in international markets and raw material costs are coming down, "which should be a nice tailwind for them over the next year," Witkowski says. Shares are trading at a deep discount to their own five-year average on a forward earnings basis, according to Thomson Reuters.

Don't look now but oil prices are roaring back ahead of the summer driving season. Just a few months ago black gold struggled to break past $40 a barrel. Now it's fetching $60, and this is only the beginning, says Rob Lutts, chief investment officer at Cabot Money Management. "With the global downturn you had a huge abrupt stop in energy exploration and development," Lutts says. "We've got a big crunch coming when the economy recovers. That's why oil can't go below $50 and I think it's going to $70." Diamond Offshore Drilling (DO) is one of Lutts's top picks, partly because it s a deep-water driller and that's where the oil is. Year over year, earnings per share are forecast to grow nearly 10% in 2009 to $10.33, according to Thomson Reuters.

The operator of the T.J. Maxx and Marshall's off-price chain stores looks to be well-poised for the critical back-to-school shopping season, says Patrick McKeever, an analyst at MKM Partners, who rates shares at Buy. Indeed, lower-price chains like Wal-Mart (WMT) and T.J. Maxx have been gaining traffic at the expense of midpriced and specialty players such as Hot Topic (HOTT) . And it s not just that budget-conscious consumers are searching for brand names at deep discounts; TJX (TJX) has also developed tremendous efficiencies. "They're in the process of taking $150 million out of their cost structure," McKeever says. "And they've got such an efficient distribution system that they can buy inventory in some instances just two to three weeks out." Tight inventory control means that gross margin -- any retailer's Achilles' heel -- should remain resilient. "Unless the consumer environment just takes another tumble, they are well positioned," says McKeever. Analysts' average price target stands at $34.50, according to Thomson Reuters, implying upside of 22% in the next 12 months or so.

The world's largest maker of lawn- and garden-care products has shown remarkable strength in its critical global consumer business. And although the seasonal planting season is already about halfway done, cash-strapped consumers are shifting to "do it yourself" lawn and garden care from "do it for me," notes Douglas Lane, an analyst at Jefferies who rates shares at Buy. More consumers are also planting vegetable gardens in these tough times, Lane says, and points out that better-than-expected results from Home Depot (HD) and Lowe's (LOW) -- big sellers of Scotts (SMG) products -- bodes well. Shares are cheaper than the market and their own five-year average on a forward basis, according to Thomson Reuters.

For a higher stakes seasonal play, look no farther than entertainment giant Walt Disney (DIS) . Better-than-expected results from theme parks and films could cause shares to pop. "You are not going to see the high-dollar trips away from home this summer," Brett D'Arcy of CBIZ says. "I could imagine a good year for theme parks and local attractions and I think it s going to be a good movie season." Disney's theme-park business has been hurt by the economic downtown, but strong promotional efforts appear to have put the worst behind it. Meanwhile, the film slate could be boffo at the box office. "Up," Disney-owned Pixar's first 3D movie, kicks off the summer blockbuster season on May 29. Jerry Bruckheimer's "G-Force" (3D animated guinea pigs) comes out in late July. With a forward price/earnings multiple of 12, shares offer a 20% discount to the S&P 500.