Eight-week planning horizon

Choose your observing weekend

Porthcawl · ranked by total moonless dark hours across Friday and Saturday. Seasonal history is context, not the chance of clear weather on those dates.

Brightened sky

Site darkness stays separate from the weather and the scheduling order.

20.3–20.9 mag/arcsec²

Next seven nights in detail · Moonless calendar · Milky Way timing

Choose a planet and find its observing times →

Moonless time rank 1

4 Dec – 5 Dec

22.0h moonless / 24.0h astronomical darkness across both nights

December seasonal context
0.1 usable nights/month on average · 2005–2024. Historical regional cloud and darkness, not this weekend’s weather odds.

Night-by-night timing & conditions

Friday

10.3h moonless · Moon 15% lit
Longest moonless stretch: 18:20–04:40

Weather not available for this night. Geometry only; recheck nearer departure.

Saturday

11.7h moonless · Moon 8% lit
Longest moonless stretch: 18:20–06:00

Weather not available for this night. Geometry only; recheck nearer departure.

Moonless time rank 2

6 Nov – 7 Nov

22.0h moonless / 22.0h astronomical darkness across both nights

November seasonal context
0.1 usable nights/month on average · 2005–2024. Historical regional cloud and darkness, not this weekend’s weather odds.

Night-by-night timing & conditions

Friday

11.0h moonless · Moon 5% lit
Longest moonless stretch: 18:40–05:40

Weather not available for this night. Geometry only; recheck nearer departure.

Saturday

11.0h moonless · Moon 2% lit
Longest moonless stretch: 18:40–05:40

Weather not available for this night. Geometry only; recheck nearer departure.

Moonless time rank 3

13 Nov – 14 Nov

19.7h moonless / 22.0h astronomical darkness across both nights

November seasonal context
0.1 usable nights/month on average · 2005–2024. Historical regional cloud and darkness, not this weekend’s weather odds.

Night-by-night timing & conditions

Friday

10.3h moonless · Moon 20% lit
Longest moonless stretch: 19:20–05:40

Weather not available for this night. Geometry only; recheck nearer departure.

Saturday

9.3h moonless · Moon 28% lit
Longest moonless stretch: 20:20–05:40

Weather not available for this night. Geometry only; recheck nearer departure.

Moonless time rank 4

16 Oct – 17 Oct

16.3h moonless / 19.3h astronomical darkness across both nights

October seasonal context
0.6 usable nights/month on average · 2005–2024. Historical regional cloud and darkness, not this weekend’s weather odds.

Night-by-night timing & conditions

Friday

8.7h moonless · Moon 35% lit
Longest moonless stretch: 21:20–06:00

Forecast cloud range: 6–6% at 1 available dark-time samples. Not full-night coverage or a probability.

Saturday

7.7h moonless · Moon 44% lit
Longest moonless stretch: 22:20–06:00

Weather not available for this night. Geometry only; recheck nearer departure.

Moonless time rank 5

20 Nov – 21 Nov

2.7h moonless / 23.3h astronomical darkness across both nights

November seasonal context
0.1 usable nights/month on average · 2005–2024. Historical regional cloud and darkness, not this weekend’s weather odds.

Night-by-night timing & conditions

Friday

2.0h moonless · Moon 84% lit
Longest moonless stretch: 04:00–06:00

Weather not available for this night. Geometry only; recheck nearer departure.

Saturday

0.7h moonless · Moon 91% lit
Longest moonless stretch: 05:20–06:00

Weather not available for this night. Geometry only; recheck nearer departure.

Moonless time rank 6

30 Oct – 31 Oct

2.7h moonless / 20.7h astronomical darkness across both nights

October seasonal context
0.6 usable nights/month on average · 2005–2024. Historical regional cloud and darkness, not this weekend’s weather odds.

Night-by-night timing & conditions

Friday

0.7h moonless · Moon 72% lit
Longest moonless stretch: 19:00–19:40

Weather not available for this night. Geometry only; recheck nearer departure.

Saturday

2.0h moonless · Moon 61% lit
Longest moonless stretch: 19:00–21:00

Weather not available for this night. Geometry only; recheck nearer departure.

Moonless time rank 7

27 Nov – 28 Nov

2.3h moonless / 23.3h astronomical darkness across both nights

November seasonal context
0.1 usable nights/month on average · 2005–2024. Historical regional cloud and darkness, not this weekend’s weather odds.

Night-by-night timing & conditions

Friday

0.3h moonless · Moon 85% lit
Longest moonless stretch: 18:20–18:40

Weather not available for this night. Geometry only; recheck nearer departure.

Saturday

2.0h moonless · Moon 76% lit
Longest moonless stretch: 18:20–20:20

Weather not available for this night. Geometry only; recheck nearer departure.

Moonless time rank 8

23 Oct – 24 Oct

0.3h moonless / 20.7h astronomical darkness across both nights

October seasonal context
0.6 usable nights/month on average · 2005–2024. Historical regional cloud and darkness, not this weekend’s weather odds.

Night-by-night timing & conditions

Friday

0.3h moonless · Moon 94% lit
Longest moonless stretch: 06:00–06:20

Weather not available for this night. Geometry only; recheck nearer departure.

Saturday

0.0h moonless · Moon 98% lit
No moonless dark window

Weather not available for this night. Geometry only; recheck nearer departure.

How to use this planner

Choose a weekend with enough moonless time, then check the weather and target outlook before travelling. Times use Europe/London and approximately 20-minute geometry samples. Friday and Saturday are ranked together; hours need not form one continuous window.

The regional NASA climate baseline counts nights with at least three hours of astronomical darkness and mean nighttime cloud at or below 30%. It does not measure telescope seeing or guarantee clear skies. No weather probabilities are inferred from monthly averages. Longer-lead forecasts have coarser sampling.

Full seasonal history and definitions →