01/06/2026
Is it Summer?
Meteorological spring is fixed to the calendar (March 1 to May 31) to help forecasters easily compare climate data year-over-year. "Real" (astronomical) spring is based on the Earth's tilt and orbit, meaning its start date fluctuates yearly (usually March 19 or 20) depending on the vernal equinox.
The Dates: March, April, and May.Why it exists: It divides the year into four exact 3-month blocks. This makes tracking weather patterns, calculating monthly averages, and comparing climate statistics incredibly straightforward.
Astronomical Spring (March 2Oth June 20th Approx)
The Dates: Starts on the vernal equinox.Why it's different: It marks the exact moment the Earth's equator passes directly through the center of the Sun's path, giving day and night roughly equal lengths. Because the Earth's orbit isn't perfectly round and takes 365.24 days, the exact timing shifts.