No. The equinox brings approximately equal day and night, not exactly 12 hours of daylight everywhere. It marks the Sun's crossing of the celestial equator, rather than a universal match between sunrise and sunset times.
The National Weather Service explains that sunrise and sunset are measured using the Sun's upper edge, not its centre. Earth's atmosphere also bends sunlight, making the Sun appear above the horizon when it is geometrically below it. Both effects extend the observed daylight interval.
The Royal Observatory distinguishes the equinox from the equilux, when daylight and nighttime are equal in length. The timing depends on latitude. For London on September 23, 2026, its guide lists 12 hours and 8 minutes between sunrise and sunset, illustrating why the two terms are not interchangeable.
The equinox is an astronomical crossing, not a promise of exactly 12 hours of daylight at every location.
National Weather Service
The NWS explains that the Sun's visible edge and atmospheric refraction make sunrise and sunset differ from the crossings of its geometric centre, so equinox daylight is not exactly 12 hours.
Based on: National Weather Service
Royal Observatory Greenwich
The September 2026 guide lists sunrise at 6:48 a.m. and sunset at 6:56 p.m. in London on September 23, giving 12 hours and 8 minutes of daylight.
Based on: Royal Observatory Greenwich
Royal Observatory Greenwich
The observatory calls the date of equal daylight and nighttime the equilux and explains that its timing depends on latitude.
Based on: Royal Observatory Greenwich
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