Spring is a dynamic period that features both winter-like cold snaps and summer-like heat waves. This seasonal volatility is a defining characteristic of this transitional time of year. The dramatic swings occur because the atmosphere attempts to balance the lingering effects of the cold season with rapidly increasing solar energy. Ultimately, spring is a season of temperature instability, which makes its weather feel highly unpredictable from one day to the next.
Two Ways to Define the Season
The perception of when spring begins often depends on which of the two common definitions is used. Astronomical spring is determined by the Earth’s orbit and the equinox, which typically occurs around March 20th in the Northern Hemisphere. This definition is fixed by the moment the sun’s path aligns with the Earth’s equator, resulting in nearly equal day and night across the globe.
Meteorological spring is a more consistent three-month block used by scientists for climate tracking and comparison. This definition groups seasons into three full months based on the annual temperature cycle, with meteorological spring including March, April, and May. This standardized grouping helps climatologists analyze temperature data more easily.
Why Spring Feels So Variable
Spring feels inconsistent because it is a battleground where the remnants of winter clash with the advancing warmth of summer. The Northern Hemisphere is rapidly gaining solar energy, but the vast reservoir of cold air and ice stored during winter takes time to dissipate. This creates a constant push and pull between contrasting air masses drawn across regions.
One day may bring a sudden warm-up, only to be followed a day or two later by a significant temperature drop, sometimes even delivering snow or sleet. This variability is intensified by the difference in how land and water absorb heat. Inland areas can warm up quickly, but coastal regions often remain cooler because large bodies of water retain winter’s chill longer.
Meteorological Causes of Temperature Shifts
The atmospheric mechanism primarily responsible for spring’s volatility is the transition of the jet stream. The jet stream is a powerful, fast-moving ribbon of air high in the atmosphere that separates cold polar air from warmer subtropical air. During winter, this current is typically further south, but as spring progresses, it begins its shift northward toward its summer position.
This transition makes the jet stream unstable, causing it to meander in large, chaotic waves. When a wave dips far to the south, it pulls frigid arctic air masses with it, resulting in a sudden cold snap. Conversely, when a wave bulges far to the north, it allows warm, moist air from the south to surge, leading to premature summer-like temperatures. This chaotic movement of the jet stream dictates the alternating blasts of cold and warm air that define spring’s temperament.
Another significant driver is the rapid increase in the sun’s angle and daylight hours. As the days lengthen after the equinox, the sun’s rays strike the ground at a much more direct angle, delivering significantly more intense solar energy. This quickly increasing energy input contributes to the rapid, albeit uneven, warming of the land surface.