DETROIT (AP) — U.S. auto sales were expected to drop slightly in July as unusually hot weather kept buyers indoors.

Kelley Blue Book predicted a 1 percent decline from last July to about 1.5 million vehicles, while auto pricing site TrueCar.com expected sales to be flat for the month. TrueCar said some automakers offered big discounts to help beat the heat.

General Motors’ sales fell 2 percent while Ford’s U.S. sales fell 3 percent. Both automakers reported declines in pickup truck sales, their best-sellers, but strong sales of big SUVs. Sales of the Ford Expedition more than doubled, while sales of the GMC Yukon were up 32 percent.

Other automakers will report sales later Tuesday.