Sunday 2026-09-20

Glacier National Park

St. Mary, MT

87 Excellent night. Moon down after 1:30am, clear skies.

Astronomical darkness 9:25pm–5:33am (8.12h) · best window 1:30am–5:33am

Milky Way core only reaches 7.3°, low enough that haze takes most of it.

Why

Cloud	100	0% cloud, essentially clear
Moon	85	waxing gibbous at 73%, sets 1:30am, dark after that
Darkness	90	8h07m of astronomical darkness, 9:25pm–5:33am
Transparency	48	Dewpoint spread 6.8°C, some haze possible