You've heard of the "January Effect," where investors sell stocks in December for tax reasons, only to buy them back in January, causing their prices to jump.

But what about other months? Retailers, for example, have some seasons that perform better than others, simply because of the nature of the business. Whatever the reason, investing based solely on the calendar is certainly not a Foolish strategy.

Still, wouldn't it be great to know ahead of time which stocks performed best at what times?

On Motley Fool CAPS, more than 110,000 investors have weighed in on more than 5,500 stocks. We've paired their opinions with data going as far back as five years to see which stocks perform best in each month. The following five companies seem to do best in August:

Stock

Market Cap

Avg. % Return-Aug

Avg. % Return-Rest of Year

CAPS Rating (5 max)

Return (YTD)

Martek Biosciences (NASDAQ:MATK)

$1.2 billion

9.86%

(0.56%)

*****

27.15%

Beacon Power (NASDAQ:BCON)

$113.9 million

63.16%

3.97%

***

(15.13%)

Javelin Pharmaceuticals (NYSE:JAV)

$119.8 million

20.00%

(9.32%)

***

(34.76%)

SulphCo (AMEX:SUF)

$253.1 million

53.27%

(6.23%)

*

(40.04%)

Evergreen Solar (NASDAQ:ESLR)

$1.4 billion

20.78%

3.63%

***

(45.92%)

Sources: America Online, Motley Fool CAPS.

Don't consider this a list of stocks to buy or sell. Before taking any action on SulphCo, for instance, we'd need to know what has driven the better August performance of the company that may hold the key to changing the properties of oil but also might burn your portfolio. We could start our research in the CAPS community, where its one-star rating suggests investors don't think it's all it's cracked up to be.

What about some of the others on the list? If August really is their month to shine, let's see which might live up to that promise.

Green around the gills
Maybe Evergreen Solar does so well in August because it reports its earnings in July. Even though it reported a 48% gain in revenues, the markets apparently didn't like the doubling of operating losses, sending shares tumbling more than 10% on the news. Evergreen is at a stage where it is building out its capacity to support future growth, a position First Solar (NASDAQ:FSLR) found itself in at the start.

Although the industry has been around for decades and some of the players, like Suntech Power (NYSE:STP), have matured into viable entities, they still pose a risk regardless of their potential. Investors like CAPS member Alex123Mal recognize this, but believe the long-term rewards mitigate the peril:

As a young investor, I have an extra bit of room for risk/reward plays built into my portfolio. I believe Evergreen Solar falls into this catagory. The recent pickup of a $3 billion contractural backlog as well as consistently meeting and beating opertaing efficencies all look good for long term investors. As a short term play, I think there are much better places to put your money. As a long term play however, I have taken a stake in [Evergreen Solar] with hopes of a ten bagger in the future.

Take it for a spin
Although flywheel storage technology might sound like a Rube Goldberg contraption, Beacon Power's advanced storage technology may help ease the demands on the nation's power grid. The Smart Energy flywheels spin at very high speeds using kinetic forces to store energy and can release the energy upon demand. They are currently being tested in California and have the potential to supplant coal- or natural gas-powered plants in regulating power grid demand.

Since it's a development stage company, Beacon Power carries a lot of risk, because it has not yet made any commercial sales of its technology and has so far only been building demonstration projects. That speculative nature of the company is understood by investors like CAPS member DCMonty25, who feel success in New York would be an important win in advancing the company's technology:

Speculative play on a power service company. If their bid to join the NYC grid proves successful, the sky is the limit for this company and its brethren. We don't necessarily need MORE energy, but we do need BETTER energy, and this company's products promise to better regulate the electric grid to prevent surges and drops with an efficiency and speed that present regulators lack. Big things are in store for this company.

A calming effect
Still, we haven't yet heard from you, and every investor's opinion counts at Motley Fool CAPS. It's free to play.

Suntech Power is a Motley Fool Rule Breakers recommendation. Try this newsletter free for 30 days to see how Fool analysts work to find the ultimate growth stocks and help you become a better investor.

Fool contributor Rich Duprey does not have a financial position in any of the stocks mentioned in this article. You can see his holdings here. The Motley Fool's disclosure policy lives in an octagonal house.