Microseason 29 of 72 · May 21–25
Firefly scouts appear at dusk
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
Firefly scouts appear at dusk
First lone fireflies test the darkening meadows.
- SESoutheast Subtropical
Fireflies scout the humid dusk
First firefly scouts pulse through warm, humid evenings. Their bioluminescence signals breeding season's arrival.
- PNWPacific Northwest
Silkworm Days—Full Canopy
Forest canopy now fully closed; understory light drops sharply. Summer breeding season opens fully: bird chicks fledge, frogs move from tadpoles toward toadlets, plant flowering accelerates.
- CACalifornia Mediterranean
Summer approaches; hills turn gold
Annual grasses senesce from green to gold. Interior heat reaches 95°F+. Fire danger official season begins. Days stretch toward 14+ hours of light.
- MWMountain West
Summer heat accelerates the growing season
High-elevation growing season accelerates with long days and warmth. Elk herds settle into high meadows. First monsoon moisture reaches north.
- MPPlains Continental
Summer Arrives Early in Wind and Heat
Beginning of summer threshold; temperatures surge; first heat waves arrive; afternoon thunderstorms build daily.
- SWSouthwest Desert
Summer arrives in dust and lightning
Monsoon rains finally arrive; afternoon thunderstorms drench bajadas.
- TRTropical / Sub-Tropical
Summer arrives in thunder
Astronomical summer begins. Temperature soars. Hurricane season looms—the Atlantic basin shifts focus skyward, watching for organized systems.
- AKAlaska Subarctic
Summer's first warmth arrives
Temperatures climb toward 70°F in interior valleys. Aurora vanishes as darkness fades. Tundra becomes a garden of blooming flowers.
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.