DETROIT (Reuters) - U.S. auto sales in September likely fell 6 percent from the same month last year as dealerships felt the mixed impact of hurricanes both this year and in 2017, industry consultants J.D. Power and LMC Automotive said on Thursday.

FILE PHOTO: Vehicles are covered with protective wrap as workers prepare the General Motors automakers display in Detroit, Michigan January 11, 2014. REUTERS/Rebecca Cook/File Photo

September U.S. new vehicle sales will likely be about 1.43 million units, down from 1.52 million units a year earlier, the consultancies said.

The forecast was based on the first 18 selling days of September. Automakers, including Ford Motor Co F.N and Fiat Chrysler Automobiles NV FCHA.MIFCAU.N, will release September U.S. sales results on Oct. 2.

General Motors Co GM.N will report quarterly sales the same day. The No. 1 U.S. automaker decided earlier this year to stop reporting monthly U.S. sales, saying a 30-day snapshot does not accurately reflect market conditions.

According to the consultancies, sales in North Carolina and South Carolina were down 12 percent in September due to Hurricane Florence, while sales were up 19 percent in areas affected by Hurricane Irma in September 2017.

Sales in September 2017 were also boosted by major replacement demand for water-damaged vehicles following Hurricane Harvey, which flooded parts of southeastern Texas in August 2017.

The seasonally adjusted annualized rate of sales for September will be 17.4 million units, down nearly 4 percent from 18.1 million units in September 2017 - the highest sales pace since 2005 - the consultancies said.

U.S. new vehicle sales fell 2 percent in 2017 to around 17.2 million units after hitting a record high in 2016.

Sales had originally been expected to drop further in 2018 as interest rates rise and more late-model used cars return to dealer lots to compete with new ones.

But with a strong U.S. economy and low unemployment, sales thus far have outperformed expectations.

LMC said it now expects full-year 2018 U.S. new vehicle sales to come in at around 17.2 million units, or virtually flat versus last year, after originally forecasting a full-year decline.

“Trade and rising interest rate risk remain real factors in the background,” LMC president for the Americas and global vehicle forecasts Jeff Schuster said in a statement.

Cox Automotive, owner of the Autotrader online automobile market and Kelley Blue Book car valuation service, said this week it expects sales to fall 7.2 percent in September to 1.41 million units.

Industry consultant and car shopping website Edmunds expects sales to fall 8.3 percent to 1.39 million new cars and trucks.