Arizona and Hawaii are the only U.S. states that do not observe daylight saving time, meaning they do not adjust their clocks forward in the spring or backward in the fall.
Understanding States Exempt from Daylight Saving Time
While most of the United States participates in daylight saving time, two states have historically chosen to opt out, maintaining a consistent clock schedule throughout the entire year. This decision is permissible under a federal law that allows states to remain on standard time permanently.
- Arizona's Approach: The majority of Arizona remains on Mountain Standard Time (MST) year-round. This means that when other states shift to Daylight Saving Time in the spring, Arizona's time effectively matches what would be Pacific Daylight Time (PDT). Conversely, when the rest of the country reverts to standard time in the fall, Arizona aligns once more with Mountain Standard Time. An important distinction within Arizona is the Navajo Nation, which does observe daylight saving time due to its expansive geographic presence that spans multiple state borders.
- Hawaii's Approach: Hawaii consistently observes Hawaii Standard Time (HST) throughout the entire year. Positioned close to the equator, Hawaii experiences minimal variation in daylight hours between seasons, which largely negates the practical need for adjusting clocks.
This consistent timekeeping simplifies daily life for residents in these states, eliminating the biannual disruption associated with time changes.
Here's a quick overview of these states:
| State | Time Zone Observation | Key Reason for No Time Change |
|---|---|---|
| Arizona | Mountain Standard Time (MST) year-round | Permitted to opt out by federal law; practical considerations due to intense summer heat make additional daylight less desirable. |
| Hawaii | Hawaii Standard Time (HST) year-round | Located near the equator, leading to consistent daylight hours throughout the year. |
