SANTA MONICA, Calif. -

After TrueCar announced its prediction for a 3.8-percent year-over-year increase in used sales last week, further forecasts for August results came pouring in.

Like this prediction from Edmunds.com: the company expects an estimated 3.22 million used cars to be sold in August, which represents a SAAR of 36.8 million.

According to Edmunds data, this is slightly down from July used sales of 3.24 million for a SAAR of 37.1 million used-car sales.

And both Edmunds and J.D. Power revealed their new-car forecasts for the month, as well.

Edmunds is predicting 1,538,959 new cars and trucks will be sold in August for an SAAR of 17.4 million, which marks a 2.1-percent increase from July, but also a 2.8-percent slide year-over-year. The site estimates that the retail SAAR, in particular, will come in at 15.3 million vehicles in August, with fleet transactions accounting for 12.1 percent of total sales.

And in a report from J.D. Power and LMC Automotive, the two companies predicted retail new-vehicle sales to hit 1.3 million units in August, marking a 1.2-percent decrease year-over-year and a retail SAAR of 13.7 million units.

Both Edmunds and J.D. Power both cited a change in the sales calendar as one of the factors behind expected year-over-year slips in new-vehicle sales.

For the first time since 2012, new-vehicle sales over the Labor Day weekend will be part of September’s sales and not included in August numbers.

Of course, as J.D. Power analysts pointed out, Labor Day weekend is traditionally the biggest new-vehicle sales weekend of the year, so this calendar discrepancy stands to make an impact.

In fact, according to J.D. Power data, in 2014, the Labor Day holiday weekend coincided with the close of the August sales month, pushing that weekend's sales to 278,878 units, or 20 percent of August sales.

Speaking on the same topic, Edmunds' director of industry analysis Jessica Caldwell didn’t seem to concerned, noting, Sales momentum in August has been strong despite recent stock market fluctuations,

She added: “The fact that we will likely see a year-over-year decline in sales isn't a troubling sign because last August ​was a monster month that included Labor Day weekend.” 

John Humphrey, senior vice president of the global automotive practice at J.D. Power, assured the industry, as well, there is no cause for “alarm.”

"On a year-over-year basis, August sales are going to appear weak, when in fact it's really a variance in the numbers created by the calendar," he said. "There certainly is no cause for alarm. In fact, the daily selling rate month-to-date in August is trending 8 percent higher than the same period a year ago, although we do anticipate the absence of the holiday in August sales will diminish that rate by the end of the month.

"Our expectation is that with Labor Day falling in September, sales that would have occurred this month are being pushed into next month. If that happens, September will move sales back to the strong trend line we've been seeing throughout the year,” Humphrey added.

As far as the sales volume forecast by manufacturer, Edmunds.com expects General Motors to come out on top with 269,759 new sales, followed by Ford with 225,834 units sold. Toyota is expected to be up next with 216,526 new-vehicles sold, with FCA in the No. 4 spot with an expected 199,091 sales. Rounding out the top five, according to Edmunds predictions, will be Honda with 156,962 new sales in August.

As for what’s in store for the next few months, the J.D. Power and LMC Automotive report pointed out a “robust performance” in July is helping drive a positive outlook for new-vehicle sales, despite the expected decline in August.

LMC automotive also pointed out a larger economic factor — recent stock market upsets — doesn't seem to be affecting the auto industry, causing the company to stick to its 2015 total light-vehicle sales forecast of 17.1 million units.

"The current stock market volatility does not seem to be having much of a negative impact on consumers as the selling rate remains well above 17 million units," said Jeff Schuster, senior vice president of forecasting at LMC Automotive. "Upside potential for the U.S. auto market is gaining momentum, as it now looks unlikely there will be an interest rate increase in September, and a delay in rising rates will most certainly assist in keeping growth on track."