The spring equinox occurs tonight. Here’s why Sacramento will see more than 12 hours of daylight Thursday
“Equinox” translates to “equal night” but most places in the Northern Hemisphere will see more than 12 hours of daylight for the first day of spring.
Updated: 8:25 PM PDT Mar 19, 2025
Meteorologist/Climate Reporter
Astronomical spring officially begins overnight Wednesday. At exactly 2:01 a.m. Pacific Time, Earth’s axis will be perfectly vertical and the sun’s most direct energy will be pointed right at the equator. This is known as the Vernal Equinox.”Equinox” translates to “equal night”, referring to the balance between the length of daylight and darkness during a 24 hour period. But if you look up sunrise and sunset times Northern California for the first day of Spring, you’ll find that our days are already about 10 minutes longer than our nights.In Downtown Sacramento, the sun will rise at 7:08 a.m. Thursday. Sunset is at 7:18 p.m. The city’s true “equal night” day was back on the 16th. What explains the shift? There are a few things.Northern California’s latitudeSince the sun’s most direct light is pointed at the equator, that is where true “equal night” is experienced during the spring and fall equinox. The farther north you go, the longer daylight is compared to the overnight hours. Downtown Sacramento sits at 38.6 degrees north of the equator and will see 12 hours and 10 minutes of daylight on the first day of spring.Fairbanks, Alaska at 65 degrees north will experience 12 hours and 17 minutes of daylight. The sun is a disc, not a pointIf you’ve ever observed a sunrise or sunset with a view of the horizon, you know it takes time for the sun to entirely appear or disappear. This is because from our vantage pint on Earth, the sun is a disc, not a single point in the sky. Sunrise is marked as the time when the top of the sun’s disc appears over the horizon. Sunset isn’t official until the top of the sun’s disk goes completely below the horizon. Measuring that way means that daylight gets a bonus minute or so.Earth’s atmosphere bends sunlightSunlight has to traverse Earth’s atmosphere before reaching the ground. On the way, particles in the atmosphere force that light to bend slightly. This bending is known as diffraction. Diffraction makes sunrises appear to occur earlier and sunsets appear to occur later. See more coverage of top California stories here | Download our app | Subscribe to our morning newsletter | Find us on YouTube here and subscribe to our channel
Astronomical spring officially begins overnight Wednesday.
At exactly 2:01 a.m. Pacific Time, Earth’s axis will be perfectly vertical and the sun’s most direct energy will be pointed right at the equator. This is known as the Vernal Equinox.
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Astronomical Spring starts tonight!The equinox occurs at 2:01 am PT. Equinox translates to “equal night” – but most of the Northern Hemisphere will see more than 12 hours of daylight tomorrow.
Watch to learn why 💐 pic.twitter.com/oX9M9IieCT
— Heather Waldman (@KCRAHeather) March 19, 2025
“Equinox” translates to “equal night”, referring to the balance between the length of daylight and darkness during a 24 hour period.
But if you look up sunrise and sunset times Northern California for the first day of Spring, you’ll find that our days are already about 10 minutes longer than our nights.
In Downtown Sacramento, the sun will rise at 7:08 a.m. Thursday. Sunset is at 7:18 p.m. The city’s true “equal night” day was back on the 16th.
What explains the shift? There are a few things.
Northern California’s latitude
Since the sun’s most direct light is pointed at the equator, that is where true “equal night” is experienced during the spring and fall equinox.
The farther north you go, the longer daylight is compared to the overnight hours. Downtown Sacramento sits at 38.6 degrees north of the equator and will see 12 hours and 10 minutes of daylight on the first day of spring.
Fairbanks, Alaska at 65 degrees north will experience 12 hours and 17 minutes of daylight.
The sun is a disc, not a point
If you’ve ever observed a sunrise or sunset with a view of the horizon, you know it takes time for the sun to entirely appear or disappear. This is because from our vantage pint on Earth, the sun is a disc, not a single point in the sky.
Sunrise is marked as the time when the top of the sun’s disc appears over the horizon. Sunset isn’t official until the top of the sun’s disk goes completely below the horizon.
Measuring that way means that daylight gets a bonus minute or so.
Earth’s atmosphere bends sunlight
Sunlight has to traverse Earth’s atmosphere before reaching the ground. On the way, particles in the atmosphere force that light to bend slightly. This bending is known as diffraction.
Diffraction makes sunrises appear to occur earlier and sunsets appear to occur later.
See more coverage of top California stories here | Download our app | Subscribe to our morning newsletter | Find us on YouTube here and subscribe to our channel
