Stars tonight · Puerto Rico
Can I see the stars tonight in San Juan?
Tonight's score for San Juan multiplies four things: how dark the sky gets, the NOAA GFS cloud forecast, the moon and the light pollution of the city. 100 is a moonless, cloudless night far from any town.
Tonight
Bad night: cloud, moonlight or light pollution hide all but the brightest stars and planets.
- Best hours
- —
- Astronomical night
- 00:00–10:00 UTC
- Clear sky (best hour)
- 96%
- Moon (best hour)
- below the horizon
Forecast from the NOAA GFS run of 2026-10-16 06:00 UTC, times in UTC. Updating live…
Tonight and the next three nights
| Night | Score | Best hours | Clear sky | Hour by hour |
|---|---|---|---|---|
| Tonight | 8 | — | 96% | |
| Sun 18 | 7 | — | 85% | |
| Mon 19 | 8 | — | no forecast yet | |
| Tue 20 | 8 | — | no forecast yet |
Score of the best hour and the run of hours within 8 points of it, times UTC. Hatched hours: no cloud forecast yet, scored on darkness and moon only.
The moon
- Phase
- waxing crescent · 36%
- Moonrise
- Fri 16 15:30 UTC
- Moonset
- Sat 17 02:32 UTC
- Next new moon
- Monday 9 November
- Next full moon
- Monday 26 October
A half moon: plan around moonset, the sky gets much darker once it is down.
The sky over San Juan
San Juan sits under an estimated Bortle 8 sky (city sky). The sky glows orange or white: the Moon, the planets and a few dozen bright stars, enough to trace Orion or the Plough. From the centre the faintest stars visible to the naked eye are around magnitude 4.1–4.5.
Dark sky near San Juan: where to drive
No spot within 100 km of San Juan gets down to Bortle 4: the light of the city and its neighbours reaches every corner of the area. The darkest sky nearby is Bortle 5, about 81 km west of the centre, 3 classes better than the centre; for a truly dark sky plan a trip beyond 100 km, ideally to a dark-sky park.
60 At the darkest spot nearby (81 km west, Bortle 5) tonight: fair, best 02:00–10:00 UTC.
That is 51 points better than the city centre.
Once there, turn your back on San Juan: its light dome rises to the east, so the darkest part of the sky is the opposite way. Give your eyes 20–30 minutes away from screens and headlights and the faint stars come out.
Get told the night San Juan turns clear and dark
The clear dark sky alert is part of LayEarth Pro: tap your spot on the stars map, press "Alert me", and get one push on the night its score reaches 60 or more, with the best hours. 7-day free trial, then 9 USD a month.
When to look up from San Juan
From San Juan, in the tropics, the Milky Way's core climbs high from April to September, and through the year both the northern constellations and southern ones like the Southern Cross take their turn.
The best nights are the week either side of the new moon: a full moon high in the sky hides all but the brightest stars, while a crescent that sets early in the evening costs almost nothing.
The Bortle scale
| Class | Sky | Faintest star | What you see |
|---|---|---|---|
| Bortle 1 | excellent dark-sky site | 7.6–8.0 | The Milky Way is bright enough to cast faint shadows, the zodiacal light and airglow are visible, and thousands of stars reach down to the horizon. |
| Bortle 2 | truly dark sky | 7.1–7.5 | The Milky Way is full of detail, faint airglow may show near the horizon, and clouds look like black holes against the stars. |
| Bortle 3 | rural sky | 6.6–7.0 | The Milky Way is rich and textured overhead; distant towns are only a faint glow low on the horizon. |
| Bortle 4 | rural/suburban transition | 6.1–6.5 | The Milky Way is clearly visible overhead but loses detail towards the horizon, where the light domes of towns rise in several directions. |
| Bortle 5 | suburban sky | 5.6–6.0 | The Milky Way is weak and washed out, visible overhead only on the best nights; light domes cover much of the horizon. |
| Bortle 6 | bright suburban sky | 5.1–5.5 | The Milky Way is at most a faint trace straight up on the clearest nights; the sky is grey up to 35° above the horizon. |
| Bortle 7 | suburban/urban transition | 4.6–5.0 | The Milky Way is invisible; the whole sky has a grey-orange glow and only the main constellations stand out. |
| Bortle 8 | city sky | 4.1–4.5 | The sky glows orange or white: the Moon, the planets and a few dozen bright stars, enough to trace Orion or the Plough. |
| Bortle 9 | inner-city sky | 4.0 | Only the Moon, the planets and the very brightest stars get through the glow; the Milky Way is out of reach. |
Questions
- Can I see the stars tonight in San Juan?
- Check tonight's score at the top of this page: 0 to 100 for the best hour of the night, from how dark the sky gets, the cloud forecast, the moon and the light pollution of San Juan (Bortle 8). Above 60 it is a good night; under 20 only the Moon, the planets and the brightest stars show.
- Where is the nearest dark sky to San Juan?
- The darkest sky within 100 km is Bortle 5, about 81 km west of the centre. The stars map shows every spot around San Juan graded for tonight.
- What time is best for stargazing in San Juan tonight?
- The best hours shown above are the run of hours within 8 points of tonight's top score. Full darkness starts when the sun is 18° below the horizon (astronomical night); a setting moon or clearing cloud often moves the best window later into the night.
- Can you see the Milky Way from San Juan?
- Not from the centre: at Bortle 8 it is lost in the glow. Drive about 81 km west (Bortle 5) on a clear, moonless night.
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How this forecast is made
The score is the LayEarth stars layer's: per hour, 100 × darkness (sun from 12° to 18° below the horizon) × clear sky (NOAA GFS low, middle and high cloud of the run of 2026-10-16 06:00 UTC, interpolated to the hour; high cloud counts 70%) × moon (its altitude and phase, computed) × light pollution (Bortle class estimated from NASA Black Marble 2016 night lights, summed within 100 km with Walker's law). It does not see haze, smoke, local horizons or lights brighter or dimmer since 2016: Bortle is an estimate from satellite data, not a meter reading. Cloud forecast reaches 48 hours; later nights are scored on darkness and moon alone. The live map grades every spot around San Juan.