According to a UFO reference book published by a couple of UFO experts, California has the most UFO sightings in the United States. The book is called "UFO Sightings Desk Reference: United States of America 2001-2015".

Every UFO sighting on the United States was collected by National UFO Reporting center and the Mutual UFO network. According to UFO experts, there have been more than 120,000 UFO sightings in the U.S. from 2001 to 2015 reported by Newstarget.

However, the Golden State experienced almost 16,000 UFO sightings. Co-author Cheryl Costa uttered that Los Angles county alone performed 40 individual states with 3200 reported UFO sightings. Additionally, Cheryl Costa had some limited number of observation for UFO hunting.

First of all, Cheryl Costa wanted to point out the reports, which was made by some individuals, reported by Sputnik. She told to SFGate, that she found the majority of the people, who were sincere about UFO sightings and just wanted to get this off their chest.

Again the authors reported that they found some similarities among the UFO that usually goes up during spring and summer, except on consistent climate states like Arizona, Texas, and Florida.

Costa believes that the people were outside more when the weather is fine. The majority of UFO sightings are from the outsider, a clear sky is pretty much helpful for a clean view of UFO author said.

A recent study suggested that UFO sightings were getting rare and rare. However, the New York native uttered that Cheryl Costa grew her interest in UFOs from her own personal UFO sightings.

Experts claimed that most of the articles regarding UFOs were not real since hardly any people were reporting to them. But recently, co-author Costa monitored the national database and bar chart of UFO sightings, she said it goes up like a rocket launch.

Cheryl Costa is a retired aerospace security engineer from 1998 to 2001. She hosted the 'X-Factor' talk radio program and covered UFO sightings and other paranormal topics.