(CNN)The Contreras Fire burning in southern Arizona has grown to 20,360 acres, prompting possible evacuations for nearby residents, officials said.
While an evacuation hasn't been mandated, the Pima County Sheriff's Department said in a news release early Monday that residents of the Hay Hook Ranch Estates area "should consider voluntarily relocating outside the affected area with family/friends."
The department reminded residents to "keep in mind" the items they might need to for pets and livestock, and to stay updated on the latest fire news.
"Emergency services cannot guarantee they will be able to notify everyone if conditions rapidly deteriorate," the department said.
The fire, burning roughly 40 miles southwest of Tucson, is 40% contained, according to InciWeb, a US clearinghouse for wildfire information.
On Friday, the Contreras Fire damaged several buildings at the Kitt Peak National Observatory, the National Science Foundation's NOIRLab (National Optical-Infrared Astronomy Research Laboratory) said in a release.
"All physical scientific observatory structures are still standing and in the case of the facilities on the (Southwest) ridge there is little visible external damage at this time; however several non-science buildings were lost," NOIRLab said.
The fire is burning in highly flammable grass and brush in steep, rugged terrain that is difficult for firefighters to access, according to InciWeb.
The blaze began June 11 on a remote ridge of a mountain range on the Tohono O'odham Indian Reservation, InciWeb says. It lists the cause as lightning.
This has been a particularly bad year for wildfires nationwide with 30,449 through June 17 -- a total higher than any of the same time periods in the past 10 years, according to the National Interagency Fire Center. About 3 million acres have been burned in the United States so far this year.
Pipeline Fire evacuation orders downgraded
Evacuation orders were downgraded Monday in areas along Highway 89 affected by the Pipeline Fire, the Coconino County Sheriff's Office said in a news release.
"Crater Estates, Moon Crater, West Alpine Ranchos, the Private Properties along Hwy 89 north from Wupatki Trails to Sacred Mountain Trading Post will be downgraded from "GO" to "SET" status," the release said, adding most of the national forest land remains closed.
"Set" status means residents must be ready or "set" to evacuate at a moment's notice, according to a post on the Coconino County Twitter account.
The fire is 50% contained and has burned more than 26,000 acres not far from Flagstaff, according to InciWeb.
Authorities are also preparing for possible flash floods from heavy storms that are expected to hit the area, according to the county website.