There is of course a good explanation why people might see UFO's , but the fact is that over 95,000 times in the last 20 years the hot line was called or the web form filled out with an observation that could not always be easily explained. The National UFO Reporting Center based in Davenport, Washington - NUFORC has been collecting data since 1974 and if the population density is taken into account, the west coast seems the spot most likely to encounter the blinking lights. The warmer months, with 4th of July being the busiest day for sightings, are obvioulsly a better time to watch the sky than a freezing winter night, but with the yearly Leonid meteor showers in November there also is a peak to be seen. The 1999 event made the NUROC record for the 90's with a very beautiful brilliant fireball according to witnesses. Another much noticed, explainable event had been a navy Missile Launch November 2015. There still are events that defy any pattern and are being explored by enthusiasts for further enjoyment.
(mouse over a dot for counts and a link for details)