Summer's last gasp!

[MickinMD ★]

Today, Sept. 21st, is the last FULL day of Summer, but Autumn doesn't officially begin until 9:04 PM EDT on September 22nd, so all or most of the daylight in North America will occur during Summer tomorrow!

Next year, the Autumnal Equinox doesn't arrive until September 23rd!

What's kind of weird is that, during Fall, we go from avg. amount of sunlight per day to the least amount of sunlight around Dec. 21st, the beginning of Winter.

Then the amount of daylight gets longer each day of Winter, right from the first!

So, why isn't Dec. 21st, the shortest day, the middle of Winter?

It's all due to the lag time between the ground getting less sunlight and the ground cooling off.  Heat rising from the ground offsets the loss of heat from the sun for a month and a half, shifting Winter back from the 3-months of shortest-daylight, around Nov. 6th to Feb. 6th, to around Dec. 21st to March 21st.

December 21st is the shortest day and, for that reason has been chosen to represent the beginning of Winter, but it's actually a little different in every area based on how much the ground absorbs and retains heat in valleys, plains, mountains, rivers and bays, etc.

In my area, those of us living within several miles of the Chesapeake Bay usually get much less snow in winter than the counties farther inland, thanks to the Bay never freezing over and the heat from the water 32+° saltwater transferring heat to the colder air.  My high school students would complain on days when all the counties surrounding ours had closed school days when ours remained open.  It also moves our Spring planting times forward.  For example, the earliest outdoor planting dates for tomatoes in Annapolis, which is the same for me, range from April 7-28 based on frost dates.  For Columbia, Maryland, about 10 miles to the west and away from the Bay, the date range from April 17 to May 8.

[ChrisL]

Winter just means shorter days and the occasional rainy day.  The weather doesn’t really change that much in coastal SoCal. 

[bikeman564™]

3 months, days get longer

[TrentonMakes]

we will see a high of only 64 on Friday and a low of 43 that evening.

not ready for that.

[Razors Edge ★]

1 hour ago, TrentonMakes said:

we will see a high of only 64 on Friday and a low of 43 that evening.

not ready for that.

I bet it will be 80s next week.  It is yo-yo season on the East Coast.

[TrentonMakes]

21 minutes ago, Razors Edge said:

I bet it will be 80s next week.  It is yo-yo season on the East Coast.

yes, I bet you're right.  There was one year within the past couple years when we had to put the heat on while it was still September.  I'd love to be able to avoid that.  The continuing theme of my life lately is "man, I can't deal with the cold like I used to".