When does summer start? Here's what to know about the summer solstice 2024

With temps in metro Phoenix edging into the 100s, you may be wondering exactly when summer officially starts.

Even though it's still spring, you're probably wearing sandals, sundresses and tank tops to beat the climbing temperatures. That begs the question: When is the real first day of summer?

The spring equinox has passed and we're just weeks away from the summer solstice. So let's get to the bottom of exactly when summer begins in Arizona and beyond, including what's the longest day of the year and whether June 21 is always the first day of summer.

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What's the difference between meteorological and astronomical seasons?

If we're going to talk about the official start to summer, we need to be specific about exactly what we mean by "summer." If that notion makes your head spin like a globe, don't worry, there's a simple explanation.

Scientists have two ways of assessing summer: astronomical and meteorological. According to the National Oceanic and Atmospheric Administration, it all boils down to this:

• Astronomical seasons are based on how the South Pole is oriented toward or away from the sun. Astronomical seasons start and end at roughly the same time every year but not necessarily on the same date from year to year.

• Meteorological seasons are divided into three-month increments based on the annual temperature cycle. Each meteorological season starts on the first day of a specific month and lasts for three months.

When does summer start?

According to britannica.com, the start of astronomical summer is marked by the summer solstice, where the path of the sun hits its northernmost point in the Northern Hemisphere.

This year, the summer solstice will land on Thursday, June 20, 2024.

When does summer start in Arizona?

With temperatures already in the low 100s in Phoenix, it's hard to believe that the official start of summer is still nearly a month away.

Astronomical summer starts in Arizona at the same time as the rest of the Northern Hemisphere: June 20, 2024, regardless of how much we think we're roasting before then.

Is June 21 always the first day of summer?

No. June 21 doesn't always mark the first day of astronomical summer. The summer solstice can land anytime between June 20-22.

This year, the official start to astronomical summer will be on June 20, 2024.

What is the longest day of summer 2024?

The longest day of summer is the summer solstice, which marks the first day of astronomical summer. The 2024 summer solstice is on Thursday, June 20.

According to timeanddate.com, "Since the Northern Hemisphere is tilted towards the sun in June, it receives more sunlight during the course of the day. The North Pole's tilt towards the sun is greatest at the solstice, so this event marks the longest day of the year north of the equator."

On the summer solstice, tropical locations receive about 12 hours of sunlight. More temperate zones farther north get about 15 hours of sunlight on the summer solstice, and the sun doesn't set at all that day over the Arctic Circle.

When does summer end?

Summer ends on Sept. 22, 2024.

When does winter start?

In 2024, winter starts on Dec. 21.

Meredith G. White is the entertainment reporter for The Arizona Republic |azcentral.com. You can find her on Facebook as Meredith G. White, on Instagram and X, formerly Twitter: @meredithgwhite, and email her at [email protected].

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This article originally appeared on Arizona Republic: First day of summer 2024: When is the longest day of the year?