How dark is the sky in Croatia?
Sky darkness for 33 towns and parks in Croatia, worked out from NASA satellite images of light at night (2025). 16 of them have skies of Bortle 4 or darker, where the Milky Way shows overhead. The darkest is Northern Velebit National Park (21.69, Bortle 4), the brightest Zagreb (18.25, Bortle 8).
19
Bortle class, 1 pristine to 9 city center
park or dark-sky place
city
Numbers like 21.95 or 16.97 are the brightness of the sky overhead on a clear, moonless night, in mag/arcsec². The scale runs backwards: a lower number means a brighter sky, from about 22 for a natural sky to about 17 in a city center.
How the readings are made
Darkest skies in Croatia
- Northern Velebit National ParkPrimorje-Gorski Kotar · Bortle 421.69
- Vrani kamenBjelovar-Bilogora · Bortle 421.63
- Papuk Nature ParkPožega-Slavonia · Bortle 421.61
- Dinara Nature ParkŠibenik-Knin · Bortle 421.60
- Paklenica National ParkLika-Senj · Bortle 421.58
Among the places on this site. Plenty of land between them is just as dark, with no town or park to name it by.
Darkest place in each county of Croatia
| County | Places | Dark places Bortle 1 to 4 | Darkest place |
|---|---|---|---|
| Bjelovar-Bilogora | 2 places | 1 dark | Vrani kamen21.63 · Bortle 4 |
| Brod-Posavina | 1 place | 0 dark | Slavonski Brod19.53 · Bortle 5 |
| Dubrovnik-Neretva | 1 place | 0 dark | Dubrovnik19.86 · Bortle 5 |
| Istria | 1 place | 0 dark | Pula19.37 · Bortle 6 |
| Karlovac | 2 places | 1 dark | Plitvice Lakes National Park21.53 · Bortle 4 |
| Koprivnica-Križevci | 1 place | 0 dark | Koprivnica19.95 · Bortle 5 |
| Lika-Senj | 2 places | 2 dark | Paklenica National Park21.58 · Bortle 4 |
| Osijek-Baranja | 2 places | 1 dark | Kopački Rit Nature Park21.33 · Bortle 4 |
| Požega-Slavonia | 1 place | 1 dark | Papuk Nature Park21.61 · Bortle 4 |
| Primorje-Gorski Kotar | 4 places | 3 dark | Northern Velebit National Park21.69 · Bortle 4 |
| Sisak-Moslavina | 3 places | 2 dark | Petrova Gora21.45 · Bortle 4 |
| Split-Dalmatia | 3 places | 2 dark | Biokovo Nature Park21.37 · Bortle 4 |
| Varaždin | 1 place | 0 dark | Varaždin19.56 · Bortle 5 |
| Vukovar-Srijem | 2 places | 0 dark | Vukovar20.24 · Bortle 5 |
| Zadar | 1 place | 0 dark | Zadar19.21 · Bortle 6 |
| Zagreb | 1 place | 0 dark | Zagreb18.25 · Bortle 8 |
| Zagreb County | 2 places | 1 dark | Žumberak-Samobor Mountains Nature Park21.29 · Bortle 4 |
| Šibenik-Knin | 3 places | 2 dark | Dinara Nature Park21.60 · Bortle 4 |