Cecile Juliette with CAL FIRE says crews are making good progress compared to Saturday when the fire broke out.
Juliette says they took advantage of higher humidity and cooler temperatures Sunday morning and grew containment lines Sunday night.
However, she warned of the heat wave coming Tuesday and Wednesday that will dry everything out even more.
Video shows aftermath of Corral fire burning in Livermore-Tracy area
SKY7 video shows aftermath of Corral fire burning in Livermore-Tracy area
Evacuation orders in the area of the Corral Fire near Tracy have been downgraded to warnings, and I-580 is back open.
Two Alameda County firefighters were hospitalized for treatment of minor to moderate burns Saturday but are expected to make a full recovery.
Juliette wants residents to be prepared with evacuation routes and have their go-bag ready.
She warned California residents of wildfire safety, noting the size and magnitude of this fire in early June when most activity is around July, August and September.
"This should highlight how dangerous firefighting is, and how dangerous it is for anyone to be near a fire, so what we're asking people is just to really pay attention to evacuation orders and to get out early because we're going to be coming in if there's a fire," Juliette said. "All fires start small so our goal is to get in there quickly so that we can keep it small, get it out and hope that people can get back into their homes quickly."
The cause of the fire is still under investigation.