Falling temperatures and light winds came at a critical juncture Wednesday for firefighters battling a blaze in the Santa Cruz Mountains that threatened hundreds of structures and forced dozens of people to flee their homes. Increased humidity and a 10-degree drop in high temperatures prompted optimism among those fighting the Loma Fire, which has burned 2,250 acres of rugged terrain since igniting Monday near Loma Prieta Avenue and Loma Chiquita Road west of Morgan Hill. Mandatory evacuation orders for Santa Cruz County residents living in the fire zone were lifted late Wednesday. “Typically when we have the cooler weather with the lower wind speeds the fire doesn’t behave as erratically, so we can get closer to the edge,” Sean Cassatt, a spokesman for the California Department of Forestry and Fire Protection, said Wednesday. The cooling trend was forecast to continue through the rest of the week, with a cold front bringing a slight chance of rain by Sunday. The relatively light winds of 5 to 10 mph in the fire zone are expected to double in strength at the end of the week, with gusts picking up to 25 mph, Mehle said.