Please note: Most locations in the Mountain Time zone are currently observing MDT, not MST. See Mountain Time.

Time zone: Mountain Standard Time (MST)

UTC -7

今ニューヨークより 3 時間だけ遅いです

Mountain Standard Time is the time in ニューヨークより 2 時間だけ遅いです when ニューヨーク is on standard time, and the time in ニューヨークより 3 時間だけ遅いです when ニューヨーク is on daylight saving time.
Mountain Standard Time does not change between summer time and winter time.
The IANA time zone identifiers for Mountain Standard Time are America/Creston, America/Dawson_Creek, America/Fort_Nelson と America/Phoenix.