Winter in the Northern Hemisphere

We are just beginning our winter season here in Bend… or wait, hasn’t winter been happening for a while? I’ve been cold and my wood-burning stove has been getting plenty of use since November. The answer to this question depends on your definition of winter, and there are two different definitions.

Astronomical winter begins around December 21 or 22. This is when the sun passes directly over the equator, creating the shortest day of the year in the Northern Hemisphere. Astronomical winter ends on the vernal equinox, around March 20.

Meteorological winter, however, is considered December, January, and February. This definition is based on the annual temperature cycle and is linked to our civil calendar. Meteorological seasons are all roughly the same number of days and start at the same time every year, which helps with calculating seasonal statistics.

 

Now that we have the timing down, what's the difference between winter in the Northern and Southern Hemispheres? In the Northern Hemisphere, many people think of snow, harsh cold, and howling winds. Is this true in the Southern Hemisphere? There are several factors that impact winters in both hemispheres and make the experience slightly different.

In the Northern Hemisphere, there are numerous large land masses at higher latitudes. In fact, Greenland and parts of Norway, Sweden, Finland, Iceland, Canada, the US, and Russia are above the Arctic Circle. Higher latitudes cause these places to generally have colder temperatures.

The Southern Hemisphere, however, has large land masses closer to the Equator, like Africa and the widest part of South America. These places tend to have warmer temperatures. In addition, there are no countries that are on or below the Antarctic Circle, other than the Antarctic continent (which is definitely quite cold!). This generally means the Southern Hemisphere experiences warmer winters.

Another interesting difference that affects cold temperatures is the amount of ocean in each hemisphere. Since water conducts and retains heat better than land, the Southern Hemisphere, which is around 81% ocean, is overall warmer. The Northern Hemisphere, on the other hand, is around 61% ocean, making it colder in comparison.

Regardless of these factors, there are still places in the Southern Hemisphere that are cold and snowy, just like there are places in the Northern Hemisphere that are warm and sunny. When you factor in that around 90% of the world’s population lives in the Northern Hemisphere, it starts to make sense that winter is usually associated with skiing, snow, and roaring fireplaces.

Learn more:

• Winter Isn't Coming
• El Niño vs. La Niña in Central Oregon
• The Precision of Winter Solstice
• A Closer Look at Snowflakes