The three clocks
Current rules follow the real time-zone and seasonal rules for your ZIP. Permanent standard uses the local standard offset all year. Permanent daylight sets that clock one hour ahead all year—even in places such as Arizona and Hawaii that do not currently change clocks.
What “first light” means
First and last light use civil twilight: the moment the Sun’s center is 6° below the horizon. Sunrise and sunset use the conventional apparent upper edge of the Sun. Terrain, weather, elevation, and an estimated ZIP center can move observed times by several minutes.
Private by design
Your ZIP lookup happens entirely in this browser. SpringAhead has no account, server-side ZIP lookup, or first-party analytics. Your last ZIP and theme choice stay on this device. The poll stores an anonymous browser identifier and your selection in a shared database; it is not linked to your ZIP.
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Sources
Postal coordinates come from GeoNames under CC BY 4.0. Solar definitions follow the U.S. Naval Observatory; current DST rules follow NIST. Results are educational estimates, not navigational or legal advice.