52 cities · US, UK, Canada, Australia, New Zealand
Clearest and darkest skies for stargazing: 52 cities ranked
Two separate questions, two separate tables. How often is the sky clear? — five years of ERA5 reanalysis, counted night by night over each city's astronomical-darkness window. How dark is the sky over the city itself? — the 2024 light-pollution atlas, plus how far you'd drive to reach a Milky Way sky. We don't blend them into a score: a clear sky over a Bortle 9 city and a cloudy sky over a Bortle 4 one are different problems.
Clearest skies: share of dark nights that stayed clear, 2021–2025
A night counts as clear when its weighted cloud cover (low 0.5 / mid 0.3 / high 0.2) averaged 20% or less across the hours of astronomical darkness — the same rule the live score uses. Nights without astronomical darkness (high-latitude summer) are left out of the denominator. Historical frequency, not a forecast.
| # | City | Clear nights | Best month | Worst month | Nights counted |
|---|---|---|---|---|---|
| 1 | Las Vegas US | 88% | June 97% | March 77% | 1,825 |
| 2 | Phoenix US | 87% | April 97% | December 74% | 1,825 |
| 3 | Tucson US | 87% | May 96% | December 76% | 1,825 |
| 4 | Flagstaff US | 78% | June 91% | March 60% | 1,825 |
| 5 | Albuquerque US | 78% | September 90% | January 67% | 1,825 |
| 6 | Los Angeles US | 71% | July 92% | May 51% | 1,825 |
| 7 | Dallas US | 70% | September 89% | February 53% | 1,825 |
| 8 | Perth AU | 68% | January 92% | July 37% | 1,826 |
| 9 | Denver US | 68% | September 82% | January 50% | 1,825 |
| 10 | San Antonio US | 63% | September 89% | May 44% | 1,825 |
| 11 | Austin US | 62% | September 89% | May 39% | 1,825 |
| 12 | Salt Lake City US | 62% | September 88% | December 25% | 1,825 |
| 13 | Brisbane AU | 61% | August 77% | March 47% | 1,826 |
| 14 | Atlanta US | 59% | October 78% | February 45% | 1,825 |
| 15 | San Diego US | 59% | August 77% | May 34% | 1,825 |
| 16 | Adelaide AU | 59% | December 77% | June 33% | 1,826 |
| 17 | Houston US | 58% | September 81% | March 39% | 1,825 |
| 18 | Nashville US | 57% | September 74% | December 39% | 1,825 |
| 19 | Washington US | 57% | October 68% | December 47% | 1,826 |
| 20 | Miami US | 57% | May 71% | September 39% | 1,825 |
| 21 | San Francisco US | 57% | May 74% | December 38% | 1,825 |
| 22 | Philadelphia US | 56% | June 66% | December 44% | 1,826 |
| 23 | Minneapolis US | 54% | July 79% | December 26% | 1,825 |
| 24 | New York US | 54% | November 65% | December 47% | 1,826 |
| 25 | Boston US | 52% | November 63% | December 42% | 1,826 |
| 26 | Sydney AU | 52% | September 64% | March 37% | 1,826 |
| 27 | Chicago US | 50% | August 71% | December 24% | 1,825 |
| 28 | Winnipeg CA | 49% | July 77% | January 23% | 1,825 |
| 29 | Calgary CA | 49% | July 72% | February 23% | 1,825 |
| 30 | Edmonton CA | 47% | September 69% | January 28% | 1,825 |
| 31 | Toronto CA | 45% | July 72% | December 14% | 1,826 |
| 32 | Ottawa CA | 45% | July 70% | December 18% | 1,826 |
| 33 | Montreal CA | 44% | September 67% | December 20% | 1,826 |
| 34 | Canberra AU | 43% | September 57% | June 29% | 1,826 |
| 35 | Wellington NZ | 43% | February 55% | June 33% | 1,826 |
| 36 | Portland US | 43% | July 90% | December 3% | 1,825 |
| 37 | Melbourne AU | 42% | February 53% | June 29% | 1,826 |
| 38 | Vancouver CA | 40% | July 85% | December 10% | 1,825 |
| 39 | Christchurch NZ | 40% | September 49% | June 31% | 1,826 |
| 40 | Auckland NZ | 40% | March 56% | October 29% | 1,826 |
| 41 | London UK | 40% | June 57% | December 17% | 1,826 |
| 42 | Seattle US | 38% | July 79% | December 8% | 1,825 |
| 43 | Bristol UK | 35% | June 49% | December 15% | 1,826 |
| 44 | Birmingham UK | 34% | August 52% | December 17% | 1,826 |
| 45 | Cardiff UK | 33% | April 47% | December 16% | 1,826 |
| 46 | Leeds UK | 32% | June 49% | December 12% | 1,826 |
| 47 | Tekapo NZ | 30% | September 37% | June 19% | 1,826 |
| 48 | Edinburgh UK | 29% | April 42% | December 14% | 1,826 |
| 49 | Belfast UK | 28% | May 43% | December 11% | 1,826 |
| 50 | Manchester UK | 27% | April 45% | December 12% | 1,826 |
| 51 | Glasgow UK | 26% | April 41% | December 12% | 1,826 |
| 52 | Queenstown NZ | 19% | February 40% | June 3% | 1,826 |
Darkest city skies: approximate Bortle class at the city centre
Zenith brightness from the David Lorenz World Atlas 2024 (EOG VIIRS), sampled at the city's public centre coordinates. Higher mag/arcsec² is darker. Bortle is an approximation from modelled brightness, never a field measurement — it says which cities are darker, not what you'll see from a given street. "To Bortle 4" is the straight-line distance in the best landward direction before the atlas reaches a Milky Way sky.
| # | City | Bortle | mag/arcsec² | To Bortle 4 | Nearest certified dark-sky place |
|---|---|---|---|---|---|
| 1 | Tekapo NZ | B4 | 21.69 | already dark | Aoraki Mackenzie 1.6 km |
| 2 | Queenstown NZ | B4 | 20.55 | already dark | Kawarau Gibbston Dark Sky Park 24.4 km |
| 3 | Flagstaff US | B5 | 20.08 | ~10 kmeast | Flagstaff Area National Monuments 13.2 km |
| 4 | Wellington NZ | B6 | 19.01 | ~10 kmeast | Wairarapa Dark Sky Reserve 48.9 km |
| 5 | Bristol UK | B7 | 18.91 | ~20 kmsouth-east | Cranborne Chase 64.8 km |
| 6 | Canberra AU | B7 | 18.79 | ~20 kmnorth | Warrumbungle Dark Sky Park 445.1 km |
| 7 | Edinburgh UK | B7 | 18.67 | ~20 kmsouth-east | Northumberland National Park and Kielder Water & Forest Park 94.1 km |
| 8 | Cardiff UK | B7 | 18.67 | ~40 kmnorth | Bannau Brycheiniog National Park (Brecon Beacons) 47.3 km |
| 9 | Christchurch NZ | B7 | 18.50 | ~20 kmnorth-west | Oxford Forest Conservation Area, New Zealand 44.4 km |
| 10 | Auckland NZ | B8 | 18.36 | ~20 kmnorth-east | Aotea Great Barrier Island 92.9 km |
| 11 | Belfast UK | B8 | 18.36 | ~30 kmwest | OM Dark Sky Park & Observatory 64.8 km |
| 12 | Leeds UK | B8 | 18.18 | ~30 kmnorth-west | Yorkshire Dales National Park 59.8 km |
| 13 | Adelaide AU | B8 | 18.16 | ~20 kmnorth-east | River Murray 87 km |
| 14 | Tucson US | B8 | 18.13 | ~30 kmnorth-east | Oracle State Park 48.4 km |
| 15 | Glasgow UK | B8 | 18.11 | ~20 kmsouth | Galloway Forest Park 86.2 km |
| 16 | Brisbane AU | B8 | 18.07 | ~50 kmnorth | Sunshine Coast 80.9 km |
| 17 | Birmingham UK | B8 | 18.03 | ~30 kmwest | Elan Valley Estate 116.9 km |
| 18 | Manchester UK | B8 | 18.03 | ~50 kmnorth | Yorkshire Dales National Park 77.6 km |
| 19 | San Diego US | B8 | 18.01 | ~40 kmnorth-east | Anza-Borrego Desert State Park 89.8 km |
| 20 | Ottawa CA | B8 | 17.99 | ~40 kmnorth-east | Parc national du Mont-Tremblant 157.8 km |
| 21 | Sydney AU | B8 | 17.97 | ~40 kmnorth-west | Warrumbungle Dark Sky Park 353.5 km |
| 22 | Portland US | B8 | 17.95 | ~40 kmeast | Cottonwood Canyon State Park 155.4 km |
| 23 | San Francisco US | B8 | 17.95 | ~50 kmnorth | Oregon Caves National Monument and Preserve 489.8 km |
| 24 | Albuquerque US | B8 | 17.93 | ~40 kmnorth | Valles Caldera National Preserve 92.2 km |
| 25 | Perth AU | B8 | 17.85 | — | none within 700 km |
| 26 | Seattle US | B8 | 17.82 | ~60 kmsouth-east | Cottonwood Canyon State Park 257.7 km |
| 27 | Vancouver CA | B9 | 17.78 | ~50 kmsouth-east | Cottonwood Canyon State Park 449.6 km |
| 28 | Austin US | B9 | 17.72 | ~40 kmwest | Milton Reimers Ranch Park 39 km |
| 29 | Melbourne AU | B9 | 17.51 | ~40 kmnorth-west | River Murray 606.1 km |
| 30 | Salt Lake City US | B9 | 17.49 | ~30 kmnorth-east | East Canyon State Park 29.9 km |
| 31 | Minneapolis US | B9 | 17.47 | ~50 kmnorth-east | Boundary Waters Canoe Area Wilderness 359.9 km |
| 32 | Boston US | B9 | 17.43 | ~80 kmnorth | Mont-Mégantic 344.3 km |
| 33 | Winnipeg CA | B9 | 17.41 | ~30 kmsouth-east | Voyageurs National Park 348.4 km |
| 34 | Montreal CA | B9 | 17.41 | ~60 kmnorth-west | Parc national du Mont-Tremblant 120.9 km |
| 35 | Toronto CA | B9 | 17.39 | ~30 kmsouth-east | Cherry Springs State Park 255.3 km |
| 36 | San Antonio US | B9 | 17.39 | ~50 kmnorth | Lyndon B. Johnson National Historical Park 92.2 km |
| 37 | London UK | B9 | 17.39 | ~50 kmsouth-west | Moore’s Reserve 76.1 km |
| 38 | Washington US | B9 | 17.37 | ~70 kmwest | Sky Meadows State Park 80.6 km |
| 39 | Calgary CA | B9 | 17.30 | ~40 kmsouth | Waterton-Glacier International Peace Park 221.9 km |
| 40 | Nashville US | B9 | 17.30 | ~70 kmnorth-east | Mammoth Cave National Park 129.2 km |
| 41 | Denver US | B9 | 17.28 | ~40 kmsouth | Florissant Fossil Beds National Monument 95.3 km |
| 42 | Phoenix US | B9 | 17.24 | ~90 kmsouth-east | Oracle State Park 156 km |
| 43 | Miami US | B9 | 17.14 | ~50 kmwest | Big Cypress National Preserve 91.5 km |
| 44 | Edmonton CA | B9 | 17.12 | ~50 kmsouth | Waterton-Glacier International Peace Park 500.4 km |
| 45 | New York US | B9 | 17.10 | ~80 kmwest | Cherry Springs State Park 336.1 km |
| 46 | Atlanta US | B9 | 17.10 | ~100 kmnorth-east | Pisgah Astronomical Research Institute 212.9 km |
| 47 | Philadelphia US | B9 | 17.05 | ~250 kmsouth-west | Sky Meadows State Park 262.8 km |
| 48 | Los Angeles US | B9 | 17.03 | ~140 kmsouth-east | Anza-Borrego Desert State Park 208.7 km |
| 49 | Houston US | B9 | 17.01 | ~80 kmwest | Milton Reimers Ranch Park 274.1 km |
| 50 | Dallas US | B9 | 16.95 | ~70 kmsouth-west | Milton Reimers Ranch Park 299.2 km |
| 51 | Chicago US | B9 | 16.84 | ~40 kmeast | Dr. T.K. Lawless County Park 146.4 km |
| 52 | Las Vegas US | B9 | 16.57 | ~40 kmeast | Grand Canyon-Parashant National Monument 145.9 km |
Questions this page answers
- Which city has the clearest skies for stargazing?
- Of the 52 cities compared, Las Vegas had the highest share of clear nights over 2021–2025: 88% of nights with astronomical darkness were clear (weighted cloud cover 20% or less), peaking in June at 97%. Source: ERA5 reanalysis via Open-Meteo, historical statistics, not a forecast.
- Which city in the United Kingdom has the most clear nights?
- London, with 40% of dark nights clear over 2021–2025 (best month June at 57%, worst December at 17%).
- Which city in Canada has the most clear nights?
- Winnipeg, with 49% of dark nights clear over 2021–2025 (best month July at 77%, worst January at 23%).
- Which city in Australia has the most clear nights?
- Perth, with 68% of dark nights clear over 2021–2025 (best month January at 92%, worst July at 37%).
- Which city in New Zealand has the most clear nights?
- Wellington, with 43% of dark nights clear over 2021–2025 (best month February at 55%, worst June at 33%).
- Which of these cities has the darkest sky over the city centre?
- Tekapo sits at about Bortle 4 (21.69 mag/arcsec² in the 2024 atlas), the darkest city centre in this set; Las Vegas is the brightest at Bortle 9. Bortle here is an approximation from modelled zenith brightness, not a field measurement.
- Why is "clear-night rate" not a forecast?
- It is how often each month's nights actually stayed clear over 2021–2025, computed from ERA5 reanalysis cloud layers over each night's astronomical-darkness window. It tells you which months tend to be clear; it cannot say whether next Saturday will be. For the next 16 nights use the live forecast.
Method and data
- Clear-night rate: ERA5 reanalysis hourly cloud cover (low/mid/high) via the Open-Meteo Archive API (CC BY 4.0), 2021–2025; astronomical-darkness windows from Skyfield with the JPL DE440s ephemeris; rule city-climatology-v1. Reanalysis assimilates satellite and surface observations — measurement-grade, but not a person standing in the field.
- Sky darkness: David Lorenz, World Atlas 2024 (EOG VIIRS, CC BY 4.0), ~0.9 km resolution; Bortle mapped from zenith brightness. Certified places: DarkSky International, straight-line distance ≤ 700 km.
- Download: both tables are built from two JSON files you can cite or reuse — city-climatology.json and city-pages.json (CC BY 4.0, attribution to the sources above). Coordinates are public city centres; no user data is involved.
- Want tonight, not the climate? Every city page has a live seven-night forecast, and the main tool scores any location on Earth for the next 16 nights.