- On March 1, the meteorological spring begins.
- This is different from the vernal equinox, which occurs on March 20.
- Weather stations are based on temperatures, not strictly on the position of the sun.
Meteorological spring arrives on Monday, and while you may feel itchy from warmer weather, you may be wondering why this happens weeks before the vernal equinox.
After a record cold stretch and repeated rounds of snow in February, spring couldn’t come soon enough for those affected by crippling power and water blackouts in Texas and surrounding states.
It turns out that spring is here, at least according to meteorologists.
The arrival of spring that you have probably heard of before is known as the vernal equinox.
That is the time when the most direct rays of the sun shine on the equator. In 2021, the spring equinox will occur on Saturday, March 20 at 5:37 am EDT. If you wake up early on a weekend morning, you can watch it this year.
Its fall counterpart, the autumnal equinox, and also the summer and winter solstices, occur in late September, June, and December, respectively, due to the tilt of the Earth’s axis when it rotates around the sun.
This changing angle of the sun throughout the year is the reason why we have so-called astronomical seasons.
(PLUS: March temperature outlook)
Why do meteorologists deviate from these seemingly concrete definitions?
It all has to do with temperatures.
When you examine the average daily maximum and minimum temperatures throughout the year, you will quickly notice a pattern.
The three coldest months of the year in the Northern Hemisphere are typically from early December to late February, while the three warmest months are typically from early June to late August.
These nice, clean three-month cubes are known as meteorological winter and summer, respectively.
And these clean three-month temperature cubes don’t line up as well with astronomical stations, for example, late December through late March.
In fact, Alaska-based climatologist Brian Brettschneider calculated that the meteorological winter from December 1 to February 28 is better suited to the colder time of year in most of the United States and Canada.
In a analysis of dozens of US cities., Brettschneider found that only Honolulu, Hawaii, had its coldest 90-day period that lasted through March.
For those who live in the northern United States, this makes sense.
It seems a bit silly when we say “winter is here” just days before Christmas, when many parts of the north have already had at least one significant snowfall or cold snap.
The meteorological spring, from March 1 to May 31, is the transition between the three coldest months and the three warmest of the year.
Another advantage of weather stations is the ease of calculating seasonal statistics, as each weather station begins on the first day of the month.
A march of rising daylight and temperatures
Most of the US will pick up a full hour of daylight when daylight savings time hits on March 14.
Even if there were no daylight saving time, most areas in the northern US would get an additional 30-45 minutes of sunlight at night in late March. The southernmost places would typically only receive 15 to 30 minutes of additional daylight during the month, if our clocks did not advance.
While March has a well-earned storm reputation, including winter storms in the western and northern US, with the sun gradually shining higher in the sky, average high temperatures generally rise by around 10 degrees. in the Midwest, Northeast, and Plains at the end of the month.
(PLUS: When to expect the first 70’s and 80’s of spring where you live)
The Weather Company’s primary journalistic mission is to report on the latest weather news, the environment, and the importance of science to our lives. This story does not necessarily represent the position of our parent company, IBM.