This summer was one of the hottest on record. In fact, July was the hottest month globally since record keeping began 140 years ago. But don't let your melted ice cream derail your quest for wealth. There are still growth stocks out there torching expectations and delivering above-average returns to investors able to keep a cool head. 

After putting more ice in our drinks, we asked three contributors at The Motley Fool for a top growth stock on their radar in the final month of summer. Here's why they're looking at Tandem Diabetes Care (NASDAQ:TNDM), ShockWave Medical (NASDAQ:SWAV), and Wayfair (NYSE:W)

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Prioritizing user experience is good for business

Maxx Chatsko (Tandem Diabetes Care): Anyone who's ever been sent home from their doctor's office with a medical device such as a Holter monitor or insulin pump knows that most of the hardware is straight out of the 1990s. They're usually big, bulky devices that look more like beepers and offer a user experience to match. That's allowed companies like iRhythm Technologies and Tandem Diabetes Care to thrive by focusing on simple devices that simply work. 

Tandem Diabetes Care has started to dominate its market with the t:slim X2 insulin pump. During the first-quarter 2019 earnings conference call, the company boasted that it had shipped 100,000 insulin pumps worldwide in the past four years. It shipped 21,258 in the second quarter alone. Management said half of all new users were entirely new to using insulin pumps.

It's easy to see why the device is catching on. The t:slim X2 insulin pump is easy to use, comes with a slick user dashboard that helps individuals with continuous glucose monitoring, and receives over-the-air software updates.

That focus on simplifying the user experience and prioritizing convenience has been great for shareholders. Tandem Diabetes Care reported $159 million in revenue and $83 million in gross profit in the first half of 2019, representing year-over-year increases of 159% and 214%, respectively. The business is growing much more quickly than management expected. That prompted a significant upward revision to full-year 2019 guidance, which now calls for $357 million in revenue at a gross margin of 54%. 

Given the current growth trajectory, and the likelihood that the company will begin generating operating profits in the second half of 2019, investors with an eye on growth might want to give Tandem Diabetes Care a closer look.

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Growth potential galore 

Brian Feroldi (ShockWave Medical): Atherosclerosis, or the gradual buildup of fatty deposits along artery walls, is a very common medical problem in adults. Left untreated, the deposits can gradually become calcified and blood flow can be restricted. That can lead to all kinds of life-threatening medical problems like strokes, heart attacks, and more. 

A common way to treat a clogged artery is with a stent or a balloon. However, in some cases, the calcium is too hardened for a balloon or stent to be effective. This is a problem that an innovative medical device maker named ShockWave Medical is working to solve.

ShockWave has developed a miniaturized balloon that uses small sonic waves to break apart the calcium from the inside. Sonic waves are an attractive therapy because they crack apart calcium but do not affect soft tissue in the surrounding area. That makes this therapy effective and extremely safe to use.

ShockWave is growing at breakneck speed as it works to bring this innovative therapy to more patients. The company rang up revenue growth of 339% last quarter. While it is still working off of a very small base, the huge pace of change shows that the medical community is warming up to its technology.

The good news for investors is that ShockWave is still in the very early innings of its growth trajectory. Management believes that its total addressable market opportunity is worth several billion dollars, which is several orders of magnitude larger than the $33 million to $36 million that it expects to haul in during 2019. 

ShockWave's valuation reflects that huge growth potential -- shares are currently trading for 66 times trailing sales -- which is a risk that potential investors need to keep in mind. I still think that taking a small position in the stock today and gradually adding over time makes sense since the opportunity ahead is so massive.

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Winning share in a surging market

Demitri Kalogeropoulos (Wayfair): The latest earnings report from Wayfair contained the same growth highlights that investors have been seeing for over a year now. The e-commerce specialist trounced management's sales targets as it soaked up market share at home and established its footing in newer markets like Canada and Germany.

Yet Wayfair's shares have dropped thanks to the combination of worries about ballooning losses and the falling stock market. It's true that red ink expanded to more than 6% of sales in the fiscal second quarter and might worsen further over the next few months as the company ramps up hiring ahead of the holiday season selling spike.

That's a short-term problem, though, and Wayfair's broader earnings strength is clear from metrics like gross profit margin and average spending per customer, which have hit new highs lately. Thus, investors who have faith in the chain's global ambitions might want to take advantage of the recent volatility to buy Wayfair's stock after the dip. A tough third quarter for profitability is likely to simply pave the way for another record holiday season for the disruptor, after all.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.