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Ever notice how the dates we talk about on TV for the start of seasons don’t always match what your calendar reads? Take winter, for example. On December 1st, we declare, “Winter has started!” But then you glance at your desk calendar and think, Wait a minute… are these people okay? No, we haven’t lost our minds (promise). There’s actually a good reason for the confusion, and it’s all about why there are two dates for the start of winter. Let’s break it down.
The astronomical start of winter is December 21:
Winter officially kicks off at 3:19 a.m. Central Standard Time this Saturday. Why such an oddly specific time? Well, that’s the exact moment when the sun’s direct rays reach their southernmost point, shining right over the Tropic of Capricorn at 23.5° in the southern hemisphere. This is as far south as those rays go before they start their journey back toward the equator. Notice, I haven’t said a word about temperatures? That’s because astronomical winter isn’t about how cold it feels, it’s all about the sun’s relationship with Earth. Cool, right? (Pun totally intended!)
There are some really cool things about this day:
- It is the shortest day of the year. The Sun is above the horizon for 10 hours 13 minutes 59 seconds.
- It is the longest night of year.
- The sun angle is at its lowest, so we get the longest shadows of the year.
- There is no daylight at the Arctic circle.
- The southern hemisphere gets their longest day of the year, and it is their start of summer.
Why we have seasons:
Did you know the Earth doesn’t orbit the sun standing straight up and down? It’s tilted on its axis at 23.5°. That tilt is why, we have seasons. Without this tilt our weather would be the same year-round! During the start of spring and fall, the sun’s direct rays shine right over the equator. Fast forward to the first day of summer in 2025. June 20 is when the sun’s rays hit their northernmost point over the Tropic of Cancer in the northern hemisphere. But here’s where it gets tricky: the exact time the seasons start is always different. Why? Because Earth’s orbit isn’t a perfect circle, it’s elliptical. That means it doesn’t sync perfectly with our calendar. For winter, the start date usually falls on December 21 or 22, but every so often, it can sneak in as early as the 20th or as late as the 23rd.
The meteorological start of winter is December 1:
Alright, let’s talk temperatures. While astronomical winter is all about the Earth’s dance with the sun, meteorological winter is based on something much more relatable, how cold it gets. Meteorologists like to keep it simple, so we break the year into neat 3-month chunks. For winter, that means the coldest months: December, January, and February. For summer, it’s the hottest: June, July, and August. This setup isn’t just for convenience, it’s super handy for tracking things like weather records, farming, and even planning business needs. But here’s the kicker: the closer you get to the equator or the poles, temperatures tend to level out. For those of us living in the “in-between,” mid-latitudes, this 3-month system works like a charm. Keeping track of the seasons is both practical and scientific.
My former professor:
Back in meteorology school at Mississippi State, one of my professors Jeff Haby shared an interesting idea about how we should rethink the seasons. He suggested if we really want the seasons to match up with temperatures, we should make summer and winter four months long, leaving just two months each for spring and fall.
Here’s how he explained it:
“Summer: June through September (4 months), Fall: October and November (2 months), Winter: December through March (4 months) and Spring: April and May (2 months). This season structure would fit the temperature patterns more closely. The mid-latitudes tend to have long summers and long winters with a quick temperature change during Fall and Spring. The notion of seasons is a “human construct” that tries to fit reality in some way. The season structure now in place could be changed with respect to the mid-latitudes to mirror reality more closely."
What do you think? You can always write me at: ayanez@kprc.com or message me on Facebook, Instagram or X at @kprc2anthony.
I’ll be taking next week off, so my next article will be in the new year. See you in 2025!
