Daylight Hours in Antarctica: Autumn & Spring Transition Explained

Antarctica's extreme latitude creates the planet's most dramatic seasonal light cycles. At the South Pole (90°S), there is only one "day" and one "night" per year—each six months long. Coastal stations experience less extreme but still profound transitions.

Autumn (March – May): The Long Fade

• March 21 (Autumn Equinox): Sun circles horizon, 12 hrs day/night everywhere.
• Late March – April: Sun dips below horizon at pole; coastal stations lose ~20–30 min/day.
• May: Civil twilight (sun <6° below horizon) persists at coast; pole enters full darkness.
• June 21 (Winter Solstice): Maximum darkness. Pole: 24-hr night. Coast (e.g., McMurdo 78°S): ~4–6 hrs civil twilight; no true sunrise.

Spring (September – November): The Long Return

• September 23 (Spring Equinox): Sun returns to horizon at pole; 12 hrs day/night globally.
• Late Sept – Oct: Coastal stations gain ~20–30 min/day; pole in continuous twilight.
• November: Sun rises at pole (Sept 21–23); climbs higher daily. Coast: 18–24 hrs daylight by late Nov.
• December 21 (Summer Solstice): 24-hr daylight at pole; coast: midnight sun.

Coastal Examples (2024)

Key takeaway: Autumn = rapidly diminishing light → polar night. Spring = rapidly increasing light → midnight sun. The transitions are swift (weeks), not gradual like mid-latitudes.