DENVER (KDVR) — If you’ve been noticing the sun setting earlier and earlier as the days go by, you aren’t just seeing things.

Whether you’re excited about the longer nights to come or wish the long summer days would last forever, afternoon sunsets in Denver are on the way. It’s just a matter of time.

In fact, as of Sept. 13, there is only a week left until the sun starts setting before 7 p.m.

End of summer, start to fall

According to the National Oceanic and Atmospheric Association, Sept. 20 is the last day of 2023 that the sun will set after 7 p.m. Specifically, it will set at around 7:01 p.m.

Three days later, on Sept. 23, astronomical fall begins with the fall equinox. This is the day that the sun rises and sets at the exact same point in the sky.

Interestingly, in Denver at least, it takes until Sept. 26 for the sun to set and rise exactly 12 hours apart. On that day, the sun will rise at 6:51 a.m. and set at 6:51 p.m.

Doesn’t the sun already set before 7 p.m.?

If you live in the Front Range, you may already think that the sun sets before 7 p.m. because it definitely starts to get dark before that.

You can blame the mountains for that phenomenon.

Sunrise and sunset times are calculated based on when the sun begins to cross the horizon. If anything blocks that horizon — for example, the Rocky Mountains — it will seem like the sun sets earlier than it actually does.

As you might expect, the Front Range does not, however, have that same issue with the sunrise. With the seemingly never-ending flat land of the plains to the east, there is nothing there to block the horizon.