More than 100 people signed up to speak at the meeting, which began at 7 p.m. and continued late through the night.
The City Council was to vote on an appeal after the hearing submitted by a citizens' group opposed to the plan.
The plan by the Islamic Center of Temecula Valley has sparked heated debate.
Some who oppose the building of the mosque said it could become a haven for Islamic extremists.
"It confuses when we hear and read that mosques are used to call its members to insurrection and jihad," said Pastor Terrell Barry of the Orchard Christian Fellowship.
City officials said the Islamic Center of Temecula Valley has met all of its requirements and went beyond, getting a traffic study and putting in more parking.
Mosque members said it is misinformation and fear that's driving opposition.
"We are as American as they are," Hadi Nael of the Islamic Center of Temecula Valley. "We have the right to exercise our religion like everybody else. They just have to let their fears down."
