* On average. And by these definitions, which are just one or two ways of looking at this topic. Really, it's winter whenever you decide to switch to the big coat and put the shovel in the car. | Also: Here's a larger, easier-to-read version of this graph.

Winter starts December 21 -- by the astronomical definition. And it starts December 1 by -- the meteorological definition.

But when does it really start in Albany?

Inspired by a chart and discussion on Twitter today attempting to mark the start of seasons in various places around the country based on normal temperatures, we figured it'd be interesting to look at the daily temperatures in Albany in order to define what you might call the "statistical" seasons. That is, when the seasons start based on what the temperatures actually are and not what the calendar says.

Of course, you can interpret numbers all sorts of ways. And in this case we ended up doing it two ways:

+ Breaking the year up into (roughly) four quarters according to normal temperatures. Winter's the coldest 25 percent of the days each year, summer's the warmest 25 percent, and spring and fall are what's in between. Looking at it this way, winter starts December 5 and lasts until March 10.

+ Looking at the distribution of temperatures here throughout the year and defining winter and summer as the days when temperatures are either in the bottom or top 25 percent of the distribution. Spring and fall are everything in between. Looking at it this way, winter starts December 1 and lasts until March 20.

And: See resulting chartage above. Don't worry, we've included a larger version here, along with a bonus graph.

Here's a bit more explanation and weather nerding...

Larger charts, please

They're above in large format -- click or scroll all the way up.

The bonus chart is just a graph of the normal highs and lows for every day of the year.

Where these numbers are from

We pulled together the "normal" high, low, and average temperatures for each day of the year from the National Weather Service Albany website. They're the 30-year normals, which currently cover 1981-2010.

The seasonal definitions are based on the average temperature for each day. (We ignored February 29.)

Additional weather nerding

+ The year cut into quarters is kind of a nice, neat way of thinking about this, but it probably doesn't match all that well with the way people experience the seasons. Looked at this way, spring stretches into June, summer seems short, and fall claims a part of December -- all of which feels off.

+ The seasons defined by temperature distribution feels more accurate. But even with that you run into those in-between seasons like mid March when it's now "spring," but the high temperature is typically only about 44. (In fact, under this approach the winter-to-spring switch "happens" not because of a change in high temperature but because of an increase in the low temperature, just bumping up the average temperature.)

+ Using the temperature distribution approach, the lengths of seasons here end up being:

Winter: 105 days

Spring: 66 days

Summer: 124 days

Fall: 70 days

+ To us, spring often feels short here. And, based on this way of thinking about the seasons, maybe it actually is! That's backed up in part by the chart of daily normals. You can see see how the typical daily temps climb a bit more rapidly through the spring compared to the fall.

+ It would be interesting to run these numbers again when the new set of 30-year normals are out in a few years. Albany winters -- that is, December through February -- have been getting steadily warmer on average over the last century.

+ If you're interested in more about this topic, head over to this blog post by climatologist Brian Brettschneider. It was one of his charts that was the seed for that Twitter thread from Eric Fisher that inspired this post

+ More seasons here: growing seasons and snowfall seasons.