When Is Winter?

On an on-line forum I check frequently, RV.Net,  there has been talk for weeks about “winterizing” motor homes and trailers – or about heading south to Florida, Arizona, or the Rio Grande Valley.  Lots of entries from folks from Illinois and Ontario crying about the fact that their camping is over for another year. 

Retailers put  Christmas displays up this year as they took the Halloween stuff down.

Here at Boggy Thicket, the overnight low has been down to 40 once, but it was in the 80’s yesterday afternoon.  About half of the leaves we expect to fall are still on the trees, and we’re running around in shorts.  Meanwhile, there have already been snowstorms on the West Coast and blizzards on the Western slopes in Colorado.

Taken all together, these apparently inconsistent bits of data might lead you to ask, “ So just when does winter start, anyway?”

Here’s a pretty good explanation from the WeatherBug:

By Chief Meteorologist, Mark Hoekzema

Most people consider the first day of winter to be the Winter Solstice, this year occurring on Tuesday, December 21. This is because, astronomically, the sun will be directly overhead of the Tropics of Capricorn; the southern-most point the sun will be directly overhead during any particular year.

As the earth rotates around the sun, at different times of the year the sun will be situated directly overhead at midday. The day the sun is straight up at noon over the Tropic of Cancer and Capricorn (23.5 degrees N and S latitude) are the summer and winter solstices, respectively. The Vernal (Spring) Equinox is the day the sun is again highest in the sky at noon over the equator as the apex progresses north.

Many refer to Astronomical Winter on December 21, as the first "official" day of winter. Most meteorologists will argue that winter has been well under way by then and they have been enjoying at least three weeks-- if not longer-- of "winter" already.

Meteorologists observe seasons over different time periods. Meteorological winter begins on December 1, spring begins on March 1, summer begins June 1 and fall begins on September 1.

There are a couple of very important reasons why this is the case. The most important is for climate record-keeping. Climatologists require set time periods to calculate averages and do seasonal comparisons over the years. Astronomical dates will fall on different days depending on the year and keeping seasonal climate records based on those dates would be confusing and inaccurate.

A second reason is that weather-wise, it makes more sense around the globe. For example, much of the northern hemisphere is entrenched in winter weather by December 1. Cold winds blow, snowstorms are crossing the country, and most areas north of the mid-latitudes have experienced their first freezes. December 21 is the first day of astronomical winter, but most regions have had nearly a month of winter weather by that day.

In spring, mild surges of air from the south are becoming a regular occurrence and severe weather threats begin to kick in by March 1. The heat of summer has been experienced in most areas across the country by June 1 and the heat of summer is waning by September 1.

For me, perfect weather would be found on an island in the Caribbean or South Pacific where the sun shines every day and the temperatures range from mid-80s during the day to mid-possibly low-70s at night. 

  

A lot of folks might find that boring – we have friends who moved to Houston from various northern states and bemoan the loss of four distinct seasons - but for my money, if I get a longing for cold and snow, I can always hitch up and head for the Rockies.

Most of the various forecast services do seem to agree that La Nina will bring us a warmer, drier winter than the one we experienced last year.  I’m all for that.