Meteorological vs. astronomical spring
Many are eagerly anticipating the first day of spring, especially after the wave of warmth and sunshine this past week.
Temperatures have risen by up to 75 degrees since last Friday when early morning lows bottomed out around 10 to 15 degrees below zero. The five-day stretch of afternoon 60s has melted even the largest piles of snow left over from January’s blizzard and subsequent snowfalls, a sight most will not miss.
Spring has certainly been in the air, although the calendar has yet to catch up, with several weeks until the “official” start of astronomical spring. However, this weekend will mark the start of meteorological spring, which begins on March 1 and lasts through May 31.
Meteorological spring is a widely used concept in atmospheric science for tracking weather and climate data and keeping cleaner stats for comparison from year to year and season to season. Meteorological spring is based on the annual temperature cycle, whereas astronomical spring follows the vernal equinox, determined by Earth’s position relative to the sun.
Another key difference between the two seasonal definitions is that meteorological spring always has the same number of days, while the first official day of astronomical spring can vary, usually falling on March 20 or 21. This year, it will occur on Thursday, March 20. Last year, it fell on March 19 due to the leap year.
Regardless of the date one uses to mark the start of spring, March is sure to bring warmer conditions. Average high temperatures for the region start in the upper 40s on March 1 and rise to the low 60s by March 31.
While the numbers don’t lie, they can be deceiving as daily fluctuations and variable atmospheric patterns tend to make March rather fickle when it comes to warmth. On average, St. Joseph receives just over an inch of snow during March and sometimes more depending on the year. Luckily, that snow rarely sticks around as the higher sun angle of spring is an efficient snow melter and periods of cold tend to be much shorter.
