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ERA5 climatology · 2015–2024
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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.

Clear sky by month · Denali100 − mean cloud cover · higher is better

Clearest dark months here (outlined): Jan, Feb, Mar. Faint: no night with an hour of astronomical darkness — white nights, twilight only (May, Jun, Jul). Part-faint months are dark on some nights only: dark until 11 Apr; dark from 31 Aug. 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 →

● Tonight at Denali — live →

Clearest dark skies in June

The aurora belt · Kp 3 or lessAll 70 spots

Top three: South Africa (Cape Point / Hermanus), North Dakota, Montana (Glacier NP). 23 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.

  1. 01South Africa (Cape Point / Hermanus) Africa · S52%11.1hKp 9+
  2. 02North Dakota North America · N50%1.8hKp 5+
  3. 03Montana (Glacier NP) North America · N· dark until 8 Jun44%1.5hKp 5+
  4. 04South Australia coast (Kangaroo Is.) Oceania · S42%11.2hKp 7+
  5. 05Northern Minnesota (Voyageurs) North America · N42%1.7hKp 5+
  6. 06Dunedin / Otago Peninsula Oceania · S40%11.7hKp 5+
  7. 07Michigan Upper Peninsula (Keweenaw) North America · N40%2.4hKp 5+
  8. 08Launceston Oceania · S39%11.5hKp 5+
  9. 09Christchurch Oceania · S38%11.6hKp 6+
  10. 10Hobart Oceania · S37%11.5hKp 5+
  11. 11Lake Tekapo (Aoraki Mackenzie) Oceania · S36%11.6hKp 5+
  12. 12Northern Maine (Acadia) North America · N36%3hKp 5+
  13. 13Victoria coast (Phillip Island) Oceania · S35%11.3hKp 6+
  14. 14Washington (North Cascades) North America · N· dark until 8 Jun35%1.5hKp 6+
  15. 15Patagonia (El Calafate) South America · S33%11.9hKp 9+
  16. 16Bruny Island / Cockle Creek Oceania · S31%11.6hKp 4+
  17. 17Punta Arenas South America · S30%12.1hKp 9+
  18. 18Invercargill Oceania · S30%11.7hKp 5+
  19. 19Falkland Islands South Atlantic · S28%12hKp 9+
  20. 20Stewart Island / Rakiura Oceania · S21%11.7hKp 4+
  21. 21Ushuaia / Tierra del Fuego South America · S20%12.2hKp 8+
  22. 22Queenstown / Southland Oceania · S15%11.6hKp 5+
  23. 23South Georgia South Atlantic · S7%12.1hKp 8+
clear = 100 − mean cloud cover · dark = mean hours of astronomical dark · glow = the spot's Kp for a glow

No true darkness in June

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.

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 →