As a general rule, there is a six hour time difference between European Central Time CET and east coast time or Eastern Standard Time and 9 hours difference between CET and west coast time or Pacific Standard Time. (For example when it is 6 pm or 18hr in CET (Paris, Frankfurt) it is 12 noon in New York and 9 am in Los Angeles. )
There are specific periods during the year when this time difference changes because the US does not change its winter (Standard time) to summer time (Daylight Savings Time) at the same time as the European continent. In the US, the change from Standard Time to Daylight Saving Time is normally the second Sunday in March and from Daylight Savings Time to Standard Time is the first Sunday in November. For more information regarding the official times contact the websites for the following organizations: the National Institute of Standards and Technology (NIST) or U.S. Naval Observatory (USNO).
The continental United States has 4 principal time zones: Eastern, Central, Mountain and Pacific. There are 3 hours difference between the Eastern Standard Time ( ex. New York or Washington DC) and Pacific Standard Time ( ex. San Francisco or Los Angeles). Please note that time zones to not correspond with State borders. There can be two different time zones in the same state like, Idaho, Arizona, Utah and even Florida. Alaska is located in the Alaskan Standard time zone ,a 10 hour difference between CET and Hawaii is in the Hawaii-Aleutian Standard time, an 11 hour difference between CET.
The Americans still use Latin to indicate precise times between morning and night: morning hours are A.M. (Ante Meridiem) and evening hours are P.M. (Post Meridiem). A.M. examples: 12am is mid-night and 1am is one in the morning. P.M. examples: twelve o’clock mid-day is 12pm or 12h and 1pm is 13h.