Updated, March 15, 2024
It may not feel like it on these chillier days we’ve been experiencing recently … but spring is in the air.
The spring equinox — the day when we get almost equal amounts of daylight and nighttime — is approaching. (The word itself is derived from two Latin words: Aequus, meaning equal, and nox, meaning night.)
But what exactly are equinoxes, when do they happen, why do they happen and how can you celebrate the start of spring in the Bay Area? Keep reading for all you need to know about the spring equinox — and the various ways you can celebrate in the Bay Area.
The science of seasonal change
The 2024 spring equinox (PDF) — also called the vernal equinox — will occur on Tuesday, March 19, at 9:06 p.m. PST. This is the time when we Californians can officially welcome the beginning of a new astronomical season: spring.
These seasonal changes happen through phenomena known as equinoxes and solstices. And they’re made possible thanks to the slight tilt of Earth’s axis.
During the spring equinox, the sun is shining directly over Earth’s equator. The Northern Hemisphere prepares for warmer days (spring), while the Southern Hemisphere prepares for cooler days (fall).
Our hemispheres experience opposite seasons, with roughly 12 hours of daylight and 12 hours of nighttime during equinoxes. This means that while we experience spring here in California, countries in the Southern Hemisphere, like New Zealand and Australia, are experiencing fall.
But it’s worth noting that some countries define the beginning of their seasons differently. For example, both New Zealand and Australia use the meteorological definition of seasonal change instead of the astronomical definition.
Meteorological definitions have the seasons beginning on the first day of the month, which includes the equinoxes and the solstices — not on the days of the equinoxes and solstices themselves (per the astronomical definition). So for Australia and New Zealand, fall began on March 1, instead of when their fall equinox occurs — which is on March 20, 2024, local time.
During solstices, we experience longer days or nights. These, like equinoxes, also happen twice a year, in June (summer) and December (winter).
During the summer solstice in June, Earth’s tilt receives the most sunlight in the Northern Hemisphere. The Arctic Circle receives light for a full 24 hours during this time — while at the Antarctic Circle, in the Southern Hemisphere, the sun will only appear briefly around noon. But during the winter solstice in December, it’s the opposite: During this period, the sun will briefly appear in the Arctic Circle, and it’s the Antarctic Circle that will have light 24 hours a day.
We can bask in the sun on warm summer days, have ski adventures in the winter, enjoy the fall foliage and admire wildflowers in the spring — all due to Earth’s tilt on its rotational axis and movement around the sun.
If you’re wondering why the date of the vernal equinox changes some years — last year, the vernal equinox in our hemisphere was March 20 — you can thank the fact that the Earth’s orbit around the sun isn’t exactly 365 days long. Instead, it takes an extra six hours or so to complete its journey, which is why an extra day gets added to the calendar every four years, making a leap year like 2024. That’s also why the time of the March equinox slides a little later every year.
Celebrations around the equinox
Persian New Year (Nowruz)
The spring equinox also marks the Persian New Year, or Nowruz, which means “new day” in the Persian language.
Nowruz is a very special occasion rooted in Zoroastrian traditions and dating back more than 3,000 years. It is celebrated by Iranians, Afghans and people from many other cultures around the world. It involves spending time with loved ones and eating delicious foods while welcoming spring. In this explainer from 2021, KQED’s Kyana Moghadam shares reflections from Northern California’s Iranian American community.
You’ll find several events celebrating Nowruz around the Bay Area this month, including a Persian New Year Celebration with the Bay Area Persian Music Ensemble at the West Valley Branch Library in San José at 2 p.m. on Sunday, March 17.
Easter
Easter is celebrated on the Sunday after the first full moon, which occurs after the spring equinox. For those celebrating this year, Easter will be observed on Sunday, March 31, since the first full moon occurs on Monday, March 25.
If you’re looking for a free egg hunt for the whole family, there are several happening at the Mill Valley Spring Faire on Saturday, March 23, with different events for different ages.
Ostara
Ostara is a Wiccan holiday that celebrates fertility, rebirth and renewal. Rituals during Ostara can include learning about the goddess Ostara, meditation, going outdoors to celebrate the awakening of nature and more. Because spring is the start of the growing season, a common way to celebrate Ostara is to plant seeds.
Other cultural or religious holidays, such as the Moon Festival, Holi, Christmas, Higan and Navaratri, are also celebrated around the equinoxes in March and September.