The tree, which was about 5 feet in diameter and 125 feet tall, flattened a car and took out some fencing in the 900 block of N Hill Avenue. There were no injuries or damage to homes reported.
Authorities said they were worried the 100-year-old tree fell after the ground became saturated and the roots gave way.
With more wet weather just days away, officials said they were concerned that the area could see similar incidents.
"With anticipated rain this weekend, too, that is a big fear for us with these trees," Lisa Derderian with the Pasadena Fire Department said. "We really encourage people to do the annual tree trimming and continue to maintain the vegetation around the homes because of situations that could occur like this."
A storm system is expected to bring heavy rainfall to Southern California on Friday and Saturday.
Officials urged residents to check and keep an eye on large trees near their homes during the wet weather.