Why Doesn't Hawaii Observe Daylight Saving Time?
Hawaii remains on standard time throughout the year. NIST identifies Hawaii among the U.S. jurisdictions that do not observe daylight saving time. The result is simple for clocks: Hawaii stays on HST at UTC−10:00 while most mainland locations advance one hour during the federal DST season.
No March clock changeWhen most DST-observing U.S. locations spring forward, Hawaii remains on HST.
No November clock changeWhen those locations fall back, Hawaii's clock still remains unchanged.
Practical effectThe Hawaii–California difference is three hours during California's PDT season and two hours during PST.
Hawaii-Aleutian Time Zone: What the Name Really Means
Federal regulation 49 CFR §71.12 defines the Hawaii-Aleutian standard time zone as including the entire State of Hawaii plus the part of Alaska's Aleutian Islands west of 169°30′W.
That shared federal zone name does not mean Hawaii and the western Aleutians follow identical seasonal clocks. Hawaii stays on HST/UTC−10. Western Aleutian communities such as Adak observe daylight saving time, moving to UTC−09 during the DST season.