| # | City | Bortle (est.) | Brightness | 2 classes darker |
|---|---|---|---|---|
| 1 | Porto | 8–9 | 255 | ~25 km W |
| 2 | Lisbon | 8–9 | 255 | ~25 km SW |
| 3 | Algueirão | 8–9 | 255 | ~25 km W |
| 4 | Braga | 8–9 | 255 | ~25 km NNE |
| 5 | Felgueiras | 7–8 | 234 | ~25 km ESE |
| 6 | Leiria | 7–8 | 255 | ~25 km WNW |
| 7 | Setúbal | 7–8 | 255 | ~25 km SSW |
| 8 | Aveiro | 7–8 | 231 | ~25 km WSW |
| 9 | Coimbra | 7–8 | 255 | ~25 km ENE |
| 10 | Viseu | 7–8 | 255 | ~25 km NNW |
| 11 | Faro | 7–8 | 249 | ~25 km SSE |
| 12 | Funchal | 7–8 | 252 | ~25 km S |
| 13 | Monsanto | 7–8 | 158 | ~25 km SE |
| 14 | Évora | 7–8 | 251 | ~25 km W |
Brightness is the NASA VIIRS Black Marble 2016 value at the city centre on a 0–255 scale; 255 is saturated. Cities are ordered by estimated sky brightness, which also counts the light within 30 km.