We're rapidly losing daylight

If you've been saying to yourself, "It feels like we're losing a lot of light" the last few days, your hunch is completely correct.

We're now officially in Autumn, as marked by the Autumn Equinox on September 22. But we've actually been losing daylight since June 20 on the Summer Solstice. So why does it all of a sudden feel like we're losing a lot more light?

The reason: we gain and lose light each day unevenly through the year.

How it changes through the year

Note: all the numbers below are for Montréal. These numbers will vary depending on your location.

The day after the Summer Solstice, we only lost about 1 second of daylight. And each passing day, we slowly start to lose a bit more:

• Jun 21: 1 sec
• Jun 22: 6 sec
• Jun 23: 10 sec
• Jun 24: 15 sec
• etc...

As we move further from the Summer Solstice, we lose more and more light. A look at July:

• Jul 1: 46 sec
• Jul 10: 1 min, 22 sec
• Jul 20: 1 min, 57 sec
• Jul 30: 2 min, 23 sec

And so it goes. The daylight loss continues going up a few seconds each day until it plateaus around the Autumn Equinox:

• Sep 1: 3 min, 4 sec
• Sep 10: 3 min, 8 sec
• Sep 20: 3 min, 9 sec
• Sep 30: 3 min, 9 sec

We lose over 3 minutes of light per day

Our daylight loss peaks and stays here at over 3 minutes for a few weeks. Each day the sunrise gets later and the sunset gets earlier.

Eventually, though, that peak loss begins to go down:

• Oct 5: 3 min, 8 sec
• Oct 15: 3 min, 5 sec
• Oct 25: 2 min, 57 sec
• Oct 31: 2 min, 51 sec
• etc...

The sunrise gets later and the sunset gets earlier, but at a slower rate. Until we reach the Winter Solstice, the day with the least amount of daylight.

And here, the inverse happens: we gain light in the same slow-at-first, but then quickly-at-the-equinox pattern.

If you're feeling rowdy, you can check the exact amount we lose each day here.

Daylight Loss in Context

3 minutes per day might not sound like a lot, but draw that out over a week. That's over 21 minutes of total daylight lost!

And in a month? That's over an hour and a half!

If you add September and October's daylight loss together, it's over 3 hours. It's an extreme amount of change in just eight weeks.

A Land of Contrast

I get why people start getting bummed out this time of year. The darkness and cold temperatures can be oppressive in a place like Montréal.

Nothing I can say will make shovelling out your car in -40°C any more fun.

But compare this to a place like Quito, Ecuador (which definitely has its advantages, I'm sure). Here's the amount of daylength they get through the year:

• Mar 21: 12 hours, 6 minutes
• Jun 21: 12 hours, 6 minutes
• Sep 21: 12 hours, 6 minutes
• Dec 21: 12 hours, 6 minutes

At the Equator, you get the same amount of daylight every single day of the year.

I'm always amazed how Montréal pulls it off.

In the dead of winter, I look outside and see three feet of snow, and temporarily forget how we can possibly have amazing summer hangs.

And in the heat of summer while sitting out in a park, I forget that in six months time, I could sit here buried in snow.