# Why isn't the first day of fall... **URL:** \ **Category:** Factual Questions\ **Created:** [September 22, 2011, 3:04am UTC](https://boards.straightdope.com/t/why-isnt-the-first-day-of-fall/597143 "2011-09-22T03:04:50Z")\ **Posts on this page:** 20\ **Page:** 3
**Author:** ![GlennRayinTroy](https://avatars.discourse-cdn.com/v4/letter/g/e9c0ed/32.png) [@GlennRayinTroy](https://boards.straightdope.com/u/GlennRayinTroy)\ **Post date:** [September 27, 2011, 4:59pm UTC](https://boards.straightdope.com/t/why-isnt-the-first-day-of-fall/597143/41 "2011-09-27T16:59:24Z")
Just to get back to an answer for the OP: > [@Chronos](#): > > …But to the question the OP was probably asking, it’s not the equinox shifting relative to our calendar, but our calendar shifting relative to the equinox. Leap years are the biggest reason for this. And the reason for leap years is that a year figured by date is based on how many times the Earth has turned on its axis, while a year that is based on astronomical seasons marked by the equinoces and solstices is based on the postion of the Earth in its orbit around the Sun. Those years aren’t equal, which is why leap years exist. ---
**Author:** ![Skald\_the\_Rhymer](https://avatars.discourse-cdn.com/v4/letter/s/ecccb3/32.png) [@Skald\_the\_Rhymer](https://boards.straightdope.com/u/Skald_the_Rhymer)\ **Post date:** [September 27, 2011, 5:05pm UTC](https://boards.straightdope.com/t/why-isnt-the-first-day-of-fall/597143/42 "2011-09-27T17:05:28Z")
> [@Ximenean](#): > > If we somewhat arbitrarily declare the seasons be of equal length, then a reasonable start date for autumn would be [equinox, minus half of three months, plus temperature lag due to oceans retaining heat]. The latter varies by location but is typically about one month. That gives a date of about September 8th. But September 1st seems close enough to me. I don’t think it’s meaningful to declare that seasons are of equal length. Memphis has a distinct but fairly short winter of about two months (January and February). Our falls are about four months long. ---
**Author:** ![cochrane](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cochrane/32/10441_2.png) [@cochrane](https://boards.straightdope.com/u/cochrane)\ **Post date:** [September 27, 2011, 5:34pm UTC](https://boards.straightdope.com/t/why-isnt-the-first-day-of-fall/597143/43 "2011-09-27T17:34:06Z")
Here in Arizona we can tell it’s fall when the license plates change colors. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [September 27, 2011, 9:06pm UTC](https://boards.straightdope.com/t/why-isnt-the-first-day-of-fall/597143/44 "2011-09-27T21:06:00Z")
> [@](#): > > By that definition of “meteorological seasons”, New Orleans has only had one winter in the past 15 years (5 consecutive days below freezing) and some years, we don’t even have an autumn or spring (5 consecutive days below 10 degrees C or about 50 degrees F). That doesn’t seem like an unreasonable thing to say, to me. If it’s always warm weather where you can wear shorts and a T-shirt and run around comfortably outside, then it’s always summer. ---
**Author:** ![Autolycus](https://avatars.discourse-cdn.com/v4/letter/a/22d042/32.png) [@Autolycus](https://boards.straightdope.com/u/Autolycus)\ **Post date:** [September 29, 2011, 4:52am UTC](https://boards.straightdope.com/t/why-isnt-the-first-day-of-fall/597143/45 "2011-09-29T04:52:19Z")
> [@Telemark](#): > > Or whether it’s rabbit season or duck season. I assure you it’s wabbit season. ---
**Author:** ![An\_Gadai](https://avatars.discourse-cdn.com/v4/letter/a/d6d6ee/32.png) [@An\_Gadai](https://boards.straightdope.com/u/An_Gadai)\ **Post date:** [September 29, 2011, 5:10am UTC](https://boards.straightdope.com/t/why-isnt-the-first-day-of-fall/597143/46 "2011-09-29T05:10:28Z")
> [@Cugel](#): > > It is. 1st March every year. 1st of August. ---
**Author:** ![the\_sandman](https://avatars.discourse-cdn.com/v4/letter/t/eb9ed0/32.png) [@the\_sandman](https://boards.straightdope.com/u/the_sandman)\ **Post date:** [September 28, 2012, 5:06pm UTC](https://boards.straightdope.com/t/why-isnt-the-first-day-of-fall/597143/47 "2012-09-28T17:06:24Z")
> [@Floater](#): > > Why would the first day of autumn be on a certain date? Seasons are determined by temperature, not calendars. Seasons are determined by the relative position of the sun, not by temperature. The first day of autumn is the day that the sun crosses the 23rd parallel ---
**Author:** ![the\_sandman](https://avatars.discourse-cdn.com/v4/letter/t/eb9ed0/32.png) [@the\_sandman](https://boards.straightdope.com/u/the_sandman)\ **Post date:** [September 28, 2012, 5:09pm UTC](https://boards.straightdope.com/t/why-isnt-the-first-day-of-fall/597143/48 "2012-09-28T17:09:38Z")
> [@Cugel](#): > > It is. 1st March every year. On what planet does autumn begin in March?:rolleyes: ---
**Author:** ![pulykamell](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pulykamell/32/3166_2.png) [@pulykamell](https://boards.straightdope.com/u/pulykamell)\ **Post date:** [September 28, 2012, 5:14pm UTC](https://boards.straightdope.com/t/why-isnt-the-first-day-of-fall/597143/49 "2012-09-28T17:14:44Z")
> [@the\_sandman](#): > > On what planet does autumn begin in March?:rolleyes: Earth. Why don’t you think about it for a minute, and then maybe you’ll retract your rolleyes. ---
**Author:** ![the\_sandman](https://avatars.discourse-cdn.com/v4/letter/t/eb9ed0/32.png) [@the\_sandman](https://boards.straightdope.com/u/the_sandman)\ **Post date:** [September 28, 2012, 5:17pm UTC](https://boards.straightdope.com/t/why-isnt-the-first-day-of-fall/597143/50 "2012-09-28T17:17:31Z")
> [@GlennRayinTroy](#): > > Just to get back to an answer for the OP: > > And the reason for leap years is that a year figured by date is based on how many times the Earth has turned on its axis, while a year that is based on astronomical seasons marked by the equinoces and solstices is based on the postion of the Earth in its orbit around the Sun. Those years aren’t equal, which is why leap years exist. In fact, a year is 365 and ABOUT 1/4 days. In 4 years that makes up an extra day plus a few seconds change. To “leap” every 4 years does well enough, but in 100 years it doesn’t make enough difference. In 400 years it does. The rule of thumb is that the end of the century (ending in 00) must be divisible by 400, not merely by 4. ---
**Author:** ![Gary\_T](https://avatars.discourse-cdn.com/v4/letter/g/3ec8ea/32.png) [@Gary\_T](https://boards.straightdope.com/u/Gary_T)\ **Post date:** [September 28, 2012, 5:19pm UTC](https://boards.straightdope.com/t/why-isnt-the-first-day-of-fall/597143/51 "2012-09-28T17:19:04Z")
There is no first day of Fall in Maine, which has just two seasons – Winter and July. ---
**Author:** ![gnoitall](https://avatars.discourse-cdn.com/v4/letter/g/bb73d2/32.png) [@gnoitall](https://boards.straightdope.com/u/gnoitall)\ **Post date:** [September 28, 2012, 5:25pm UTC](https://boards.straightdope.com/t/why-isnt-the-first-day-of-fall/597143/52 "2012-09-28T17:25:38Z")
> [@Floater](#): > > Why would the first day of autumn be on a certain date? Seasons are determined by temperature, not calendars. Not really. Seasons are dictated by solar zenith latitude. Yeah. Technical. Here’s an example of what it comes down to: The moment of (Northern Hemisphere) summer solstice is the moment at which the Sun is as far north as it can be: 23.4 degrees North at local solar noon. This also means that the North Pole is pointing as nearly as it can toward the Sun. A second before or after that moment, the Earth’s North Pole “misses” pointing directly at the Sun’s corresponding pole “by that much”. It doesn’t matter what the calendar says. Astronomers predict the moment of solstice and notify the world when Northern Hemisphere summer will start. And then everyone (in Chicago, for instance) says “Summer starts on 20 June at 6:09 PM Central Daylight Time this year”. The calendar already doesn’t match the mechanical reality of Earth’s orbit around the Sun (witness leap years, as mentioned earlier), so tying seasons to the calendar would be ineffectual, since the season transitions are essential astronomical phenomena. ---
**Author:** ![Darth\_Panda](https://avatars.discourse-cdn.com/v4/letter/d/ee7513/32.png) [@Darth\_Panda](https://boards.straightdope.com/u/Darth_Panda)\ **Post date:** [September 28, 2012, 5:26pm UTC](https://boards.straightdope.com/t/why-isnt-the-first-day-of-fall/597143/53 "2012-09-28T17:26:39Z")
The Federal Energy Regulatory Commission defines Summer and June, July, and August, and Winter as December, January, and February, for what it’s worth. ---
**Author:** ![johnpost](https://avatars.discourse-cdn.com/v4/letter/j/f17d59/32.png) [@johnpost](https://boards.straightdope.com/u/johnpost)\ **Post date:** [September 28, 2012, 5:37pm UTC](https://boards.straightdope.com/t/why-isnt-the-first-day-of-fall/597143/54 "2012-09-28T17:37:54Z")
zombie or no the only people that care about the astronomical seasons are astronomers, pagans and people that need another reason for a party. most people are satisfied with the meteorological seasons using whole months. ---
**Author:** ![vd](https://avatars.discourse-cdn.com/v4/letter/v/b19c9b/32.png) [@vd](https://boards.straightdope.com/u/vd)\ **Post date:** [September 28, 2012, 5:43pm UTC](https://boards.straightdope.com/t/why-isnt-the-first-day-of-fall/597143/55 "2012-09-28T17:43:05Z")
> [@the\_sandman](#): > > Seasons are determined by the relative position of the sun, not by temperature. > The first day of autumn is the day that the sun crosses the 23rd parallel I think you mean the equator. But, hey, welcome and all that. Stick around and bring up your batting average. ---
**Author:** ![Acsenray](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/acsenray/32/4519_2.png) [@Acsenray](https://boards.straightdope.com/u/Acsenray)\ **Post date:** [September 28, 2012, 5:47pm UTC](https://boards.straightdope.com/t/why-isnt-the-first-day-of-fall/597143/56 "2012-09-28T17:47:17Z")
> [@Floater](#): > > Why would the first day of autumn be on a certain date? Seasons are determined by temperature, not calendars. > [@Philster](#): > > A season is 1/4 of the trip around the sun. Temperatures are irrelevant. > [@Lemur866](#): > > So do they have Spring, Summer, Fall, and Winter in Cameroon? So I was going to respond to these when I started reading and discovered that I already had, just about a year ago. > [@Acsenray](#): > > A season is experiential. It has nothing to do with astronomy or meteorology. Fall has begun when it feels like it is fall. > [@Acsenray](#): > > In Bengal, there are six seasons – summer, monsoon, autumn, dry season, winter, spring So you can define seasons as a quarter of the calendar year if you want, or as having a certain temperature for a certain number of days, or the relative position of the sun, but none of these definitions are fundamental. The concept of a season originates with human experience of the weather and the activities of plants and animals in the environment. Is it cold enough to wear furs? Do I need to start hoarding food for the winter? Is it warm enough to plant? Is it wet enough to make my crops thrive? Is it time for the deer to start wandering by? Is it the time for the berries to be gathered? ---
**Author:** ![Michael63129](https://avatars.discourse-cdn.com/v4/letter/m/3da27b/32.png) [@Michael63129](https://boards.straightdope.com/u/Michael63129)\ **Post date:** [September 28, 2012, 6:14pm UTC](https://boards.straightdope.com/t/why-isnt-the-first-day-of-fall/597143/57 "2012-09-28T18:14:38Z")
I have always thought of the seasons in terms of meteorological seasons, which just make more sense. For example; here is a comparison between astronomical winter and meteorological winter, based on [local weather climatology](http://www.crh.noaa.gov/lsx/?n=climate_data_wx_record) (note that this uses the AVERAGE temperature, not whatever is happening day to day): Astronomical winter (dates may vary +/- 1 day): December 21: 41/25 (average 33) March 19: 57/38 (average 47.5) Meteorological winter: December 1: 47/31 (average 39) February 28: 50/31 (average 40.5) So as you can see, if you use astronomical winter, at least for where I live, it ends nearly 15 degrees warmer (the coldest day of the year is around January 8, and even meteorological winter ends a bit warmer). Summer is more skewed, with the hottest day on average around July 19 (August 31 is about 4 degrees warmer than June 1; however, September 21 is about 10 degrees cooler than June 20). And at least lately, it seems to be getting warmer earlier in the spring (March) while Septembers have been cooler (based on actual weather data). ---
**Author:** ![Telemark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/telemark/32/372_2.png) [@Telemark](https://boards.straightdope.com/u/Telemark)\ **Post date:** [September 28, 2012, 7:24pm UTC](https://boards.straightdope.com/t/why-isnt-the-first-day-of-fall/597143/58 "2012-09-28T19:24:51Z")
> [@the\_sandman](#): > > Seasons are determined by the relative position of the sun, not by temperature. > The first day of autumn is the day that the sun crosses the 23rd parallel As mentioned when this thread was started (last year 🙂 ) it depends on what type of season you are discussing. There are several equally valid options; you are discussing the astronomical season but it’s not the only one. It does appear to be the one asked about in the OP, however, and answered in the first two posts. Welcome aboard, **the\_sandman**. ---
**Author:** ![Trinopus](https://avatars.discourse-cdn.com/v4/letter/t/2bfe46/32.png) [@Trinopus](https://boards.straightdope.com/u/Trinopus)\ **Post date:** [September 29, 2012, 12:02am UTC](https://boards.straightdope.com/t/why-isnt-the-first-day-of-fall/597143/59 "2012-09-29T00:02:51Z")
> [@pulykamell](#): > > Earth. Why don’t you think about it for a minute, and then maybe you’ll retract your rolleyes. ??? Explain, please? Is this an Australian thing? (Southern hemisphere?) My sister is a woman who has seen 45 winters…and 65 summers! (She travels a lot!) By the definition based on temperatures…I have never known a winter! ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [September 29, 2012, 12:29am UTC](https://boards.straightdope.com/t/why-isnt-the-first-day-of-fall/597143/60 "2012-09-29T00:29:44Z")
Australia is on Earth, isn’t it? And **gnoitall** , that’s certainly and indisputably what the solstices are, but there’s no fundamental reason why one has to say that the solstice is the first day of summer. [Previous page](https://boards.straightdope.com/t/why-isnt-the-first-day-of-fall/597143.md?page=2) [Next page](https://boards.straightdope.com/t/why-isnt-the-first-day-of-fall/597143.md?page=4)