Seasonality took a turn last month — with used price trends resembling those normally seen in later fall, not the dead of summer.

That’s according to the latest Guidelines report from NADA Used Car Guide, which stated prices on vehicles up to 8 years in age fell by 3.5 percent on a monthly basis in July.

This was not only the biggest recorded price drop since last October, but it was also well above NADA’s original forecast calling for a 1- to 1.5-percent decline.

“Wholesale price movement in July was decidedly out of character for the month, with depreciation more closely resembling the steeper declines usually witnessed in the fall rather than the more subtle ones observed in the heart of the summer,” NADA UCG’s senior director of vehicle analysis and analytics Jonathan Banks said in the report.

The unusual drop in prices resulted in NADA’s seasonally-adjusted used vehicle price index falling by almost three points to 123.3.

But this is still considerably higher than normal, Banks pointed out — and even with July’s large price declines, prices year-to-date are still 2.3 percent higher than they were last year, according to NADA.

As a whole, luxury segments were “hit harder” than mainstream units, Banks said. This trend popped up in the lanes as summer progressed, with luxury cars seeing some of the weakest price retention among all segments.

This past month, according to NADA data, luxury midsize car prices saw the biggest price drop, with rates falling by 3.9 percent. Banks noted this is the biggest decline on record since November 2009.

Luxury large cars, luxury midsize utilities and luxury compact cars also saw large declines, falling by a combined 3.5 percent.

Lastly, luxury compact utility prices fell by 2.4 percent.

For the non-luxury segments, the smaller units saw bigger drops than the trucks and SUV segments.

The three biggest movers among mainstream segments were the midsize and compact cars, which each fell by 3.6 percent apiece. And subcompact cars saw a drop of 3.4 percent.

SUVs and trucks continue to perform a bit better in the lanes, Banks said.

Large SUV and compact utilities saw the biggest drops among the large segments, falling by 2.9 percent apiece.

Large pickups continue to buck trends and hold stronger-than-average price retention, falling by only 1.6 percent last month.

As for what we can expect this month, NADA has updated its forecast slightly, in light of July trends.

NADA expects a price decline of 2 percent to 2.5 percent in August, and predicts this number will jump to a drop of 2.5 percent to 3 percent in September.

“Luxury car and utility prices are expected to decline the most over the period, followed by subcompact cars, midsize vans, and compact and midsize utilities,” Banks said. “Compact and midsize car depreciation should be close to the market average, while pickup losses are expected to remain minimal.”