Why Mets Think Saturday Is Spring,Already
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Winter often feels like the season that won’t end,with people desperately waiting for warmer weather and the start of spring. But meteorologists consider spring to start a few weeks before the spring – or vernal – equinox,when the season officially begins.
The reason behind this is not impatience and wishful thinking of warmer weather. It’s the result of a different loose definition of seasons that meteorologists often use.
When spring technically starts: The arrival of spring you’re probably most familiar with is the vernal equinox. That's the moment in time when the sun's most direct rays are shining on the equator.
In 2025,the vernal equinox will occur on Thursday,March 20,at 5:01 a.m. ET.
Its counterpart in fall,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 as it revolves around the sun.
This changing sun angle through the year is why we have so-called astronomical seasons.
What meteorologists use to define seasons: Meteorologists stray from those seemingly concrete definitions because of temperatures.
The coldest three months of the year in the Northern Hemisphere are usually from December through February,while the warmest three months are typically from June to August.
These nice,clean,three-month buckets are known as meteorological winter and summer,respectively.
But these three-month temperature buckets don't perfectly line up with the astronomical seasons. For example,astronomical winter lasts from December through late March.
Alaska-based climatologist Brian Brettschneider calculated that the Dec. 1-Feb. 28 meteorological winter is a better fit for the coldest time of year in most of the United States and Canada.
In an analysis of dozens of U.S. cities,Brettschneider found only Honolulu,Hawaii,had its coldest 90-day stretch extend deep into March. For the rest of the cities analyzed,the coldest period ended in late February or early March.
This matches much better with the common perception of the seasons for many:It seems a little silly when we say "winter is finally here"just days before Christmas when many parts of the north have already had at least one significant snowfall or cold snap.
By grouping the seasons by temperature,you’re also grouping the seasons more by common weather patterns.
So any calendars with snow and wintry weather on the page for December start to make more sense,even though most of the month is part of astronomical fall.
So meteorological spring – March 1 through May 31 – is the transition between the three coldest and three warmest months of the year.
Another advantage to meteorological seasons is the ease of calculating seasonal statistics since every meteorological season starts on the first of the month.
A March Of Increasing Daylight,Temperatures
Most of the U.S. will pick up a full hour of evening daylight when daylight saving time arrives on March 12 and we turn our clocks ahead by one hour.
But even if there wasn't daylight saving time,most areas in the northern U.S. would still see their sunsets move later by 30 to 45 minutes by the end of the month. There’s a smaller change in sunset time for southern locales of only 15 to 30 minutes or so.
While March has a well-earned stormy reputation,including winter storms in the West and northern U.S.,with the sun gradually shining higher in the sky,average high temperatures typically rise about 10 degrees in the Midwest,Northeast and Plains by month's end.
Sara Tonks is a content meteorologist with www.weathernow24.com and has a bachelor’s and a master’s degree from Georgia Tech in Earth and Atmospheric Sciences along with a master’s degree from Unity Environmental University in Marine Science.
