Microseason 59 of 72 · October 21–25
Leaves rattle down the gutters
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
Leaves rattle down the gutters
Peak leaf drop — the city crunches underfoot.
- SESoutheast Subtropical
Frost paints the garden
First hard frost arrives, blackening tender plants; leaves begin their audible rattle into gutters and against porches.
- PNWPacific Northwest
First killing frost
Hard freeze locks the soil. Annual plants blacken completely. The growing season is irrevocably over. Winter's cold has arrived.
- CACalifornia Mediterranean
First atmospheric river looms
Atmospheric river pressure signature clear on 5-day models. Air feels electrically charged. Waiting breaks.
- MWMountain West
First hard frost grips the basin
Killing frost overnight; frozen ground, frozen lakes beginning to freeze. The freeze line retreating downslope hourly.
- MPPlains Continental
Frost deepens through the night
Repeated hard frosts create a glazed landscape. Snow possible on cold mornings. The prairie is fully dormant — brown, brittle, and silent. Leaf fall nearly complete.
- SWSouthwest Desert
First killing frost falls
Hard freeze kills tender plants; frost damage visible on sensitive species.
- TRTropical / Sub-Tropical
Trade winds solidify
Late October locks in reliable northeasterly trade winds; the region enters its dry, temperate season definitively.
- AKAlaska Subarctic
Polar night approaches the North
Barrow begins its sixty-day polar night; northern reaches of Alaska cross into continuous darkness.
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.