Microseason 17 of 72 · March 21–25
Equinox — light overtakes dark
A five-day window of the year, read through nine North American climate regions.
Same week, nine climates
A microseason names a five-day window of the solar year. What that window actually looks like on the ground depends on where you are. Below, the same calendar window read through each of nine North American climate regions.
- NENortheast Continental
Equinox — light overtakes dark
Day and night balance; sun rises due east, sets due west.
- SESoutheast Subtropical
Light crowns the dogwood canopy
Equinox arrives. Dogwood blooms flood the forest edge—white and pink petals catching longer afternoons.
- PNWPacific Northwest
Equinox Fog Clears
Vernal equinox arrives; daylight and dark hold equal time as marine layer retreats inland each afternoon, revealing snowline high on the Cascades.
- CACalifornia Mediterranean
Light overtakes dark at equinox
Spring equinox arrives; daylight hours surge. Hills blaze with California poppy, lupine, and ceanothus. Acorn woodpeckers claim their nest cavities.
- MWMountain West
Spring equinox at the divide
Day and night balance as snowmelt quickens on the high peaks. Glacier lilies wait beneath the snowpack for their moment.
- MPPlains Continental
Equinox — Night and Day Hold Balance
The vernal equinox arrives; light and darkness divide equally as spring weather turns unpredictable and violent.
- SWSouthwest Desert
Equinox ignites the blooms
Spring equinox triggers saguaro bud swell; wildflowers peak across bajadas.
- TRTropical / Sub-Tropical
Light holds the horizon
Spring equinox—day and night equal—marks the threshold to longer light, drawing mangrove herons into courtship displays.
- AKAlaska Subarctic
Equinox — darkness yields to light
Spring equinox arrives; day length surpasses night. Interior snow remains deep, but afternoon thaws begin the breakup cycle.
About the 72-microseason calendar
A microseason is a five-day window of the solar year — long enough to notice something change, short enough that the change is specific. The year holds seventy-two of them, six per month, ordered by what the natural world is doing rather than what the clock says. Almanac calendars like this are an old American habit, kept by farmers, gardeners, and birders for centuries; Weather Story collects them into a single reference.
Each microseason is read through nine North American climate regions. The phenological events that mark a five-day window vary with ecology — the strawberries that open in the Northeast might coincide with the first magnolias dropping in the Southeast and the salmonberry blossoms unfurling in the Pacific Northwest. Same week, nine ecologies, nine readings.