The best month.
Pick a month and every watch point is ranked by its real monthly cloud cover — 2015–2024 reanalysis means, lower is better — with the spots that have no true darkness that month set apart. Or pick a spot for its twelve-month chart.
Clearest dark months here (outlined): Feb, Oct, Nov. Faint: no night with an hour of astronomical darkness — white nights, twilight only (Dec). Part-faint months are dark on some nights only: dark from 20 Jan; dark until 20 Nov. ERA5 reanalysis, 2015–2024 monthly mean. Climatology, not a forecast — a regional ~25 km grid; local microclimates are not captured. Darkness & moon calendar → Best month, all spots →
Clearest dark skies in August
Top three: Montana (Glacier NP), North Dakota, Washington (North Cascades). 43 watch points with at least one night of an hour's astronomical darkness this month, ranked by clear sky (100 − mean cloud cover); dark hours are the mean over the month's dark nights, and a part-dark month says when its darkness starts or ends. Cloud is only one of the three conditions — a clear Kp 9 spot is almost never lit; the threshold shown is each spot's own.
- Montana (Glacier NP)
- North Dakota
- Washington (North Cascades)
- South Africa (Cape Point / Hermanus)
- Michigan Upper Peninsula (Keweenaw)
- Edmonton
- Northern Minnesota (Voyageurs)
- South Australia coast (Kangaroo Is.)
- Fort McMurray
- Copenhagen
- Christchurch
- Northern Maine (Acadia)
- Jasper
- Yellowknife
- Stockholm
- Helsinki
- Victoria coast (Phillip Island)
- Estonia (Tartu / coast)
- Dunedin / Otago Peninsula
- Lake Tekapo (Aoraki Mackenzie)
- Launceston
- Oslo
- Hobart
- Patagonia (El Calafate)
- Churchill
- Whitehorse
- Bruny Island / Cockle Creek
- Invercargill
- Edinburgh
- Aberdeenshire
- Punta Arenas
- Anchorage
- Orkney
- Falkland Islands
- Caithness (north Highlands)
- Shetland
- Donegal
- Faroe Islands (Tórshavn)
- Stewart Island / Rakiura
- Ushuaia / Tierra del Fuego
- Queenstown / Southland
- Denali
- South Georgia
No true darkness in August
No night this month reaches an hour of astronomical darkness — clear or not, the aurora is not visible. Their cloud figures are shown for the record.
- Abisko · 78%
- Akureyri · 80%
- Alta · 79%
- Coldfoot / Bettles · 80%
- Dawson City · 72%
- Fairbanks · 78%
- Iceland (countrywide) · 80%
- Ilulissat · 67%
- Inari · 75%
- Iqaluit · 75%
- Ivalo · 75%
- Kangerlussuaq · 68%
- Kilpisjärvi · 79%
- Kirkenes · 77%
- Kiruna · 72%
- Lofoten Islands · 74%
- Lyngen · 78%
- Murmansk / Kola Peninsula · 75%
- Nellim · 75%
- Nuuk · 75%
- Oulu · 64%
- Reykjavík · 76%
- Rovaniemi · 71%
- Saariselkä · 76%
- Senja · 77%
- Skibotn · 79%
- Svolvær · 75%
- Tromsø · 78%
- Utqiaġvik (Barrow) · 93%
Cloud: Open-Meteo Historical Weather API (ERA5 reanalysis), cloud_cover_mean (daily), averaged by calendar month, 2015–2024. Climatology, not a forecast — a regional ~25 km grid; local microclimates (a valley's "blue hole") are not captured. Darkness: astronomical (sun below −18°) computed for the 15th of the month at each spot. Night-by-night darkness & moon → Season sheet (PDF) → Plan the trip →