The fire erupted shortly before 1 p.m. near the intersection of Granite Hill Drive and Pyrite Street, according to Cal Fire Riverside.
No injuries were reported.
In addition to the evacuation of the Discovery Center, Granite Hill Drive was closed to traffic.
Firefighters responded on the ground as Phos-Chek was dropped on the flames from overhead.
The cause of the fire was unknown.
Fire officials initially said 100 acres had burned. The estimation was later downsized to 60 acres.
The evacuation order was lifted after firefighters succesfully contained the blaze.