Eight-week planning horizon

Choose your observing weekend

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

Natural-dark sky

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

21.9–21.9 mag/arcsec²

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

Choose a planet and find its observing times →

Moonless time rank 1

6 Nov – 7 Nov

20.0h moonless / 20.0h astronomical darkness across both nights

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

Night-by-night timing & conditions

Friday

10.0h moonless · Moon 3% lit
Longest moonless stretch: 19:20–05:20

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

Saturday

10.0h moonless · Moon 1% lit
Longest moonless stretch: 19:20–05:20

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

Moonless time rank 2

4 Dec – 5 Dec

18.3h moonless / 20.7h astronomical darkness across both nights

December seasonal context
3.0 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 12% lit
Longest moonless stretch: 19:20–04:00

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

Saturday

9.7h moonless · Moon 6% lit
Longest moonless stretch: 19:20–05:00

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

Moonless time rank 3

13 Nov – 14 Nov

14.3h moonless / 20.7h astronomical darkness across both nights

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

Night-by-night timing & conditions

Friday

7.7h moonless · Moon 23% lit
Longest moonless stretch: 21:40–05:20

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

Saturday

6.7h moonless · Moon 31% lit
Longest moonless stretch: 22:40–05:20

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

Moonless time rank 4

16 Oct – 17 Oct

12.0h moonless / 20.0h astronomical darkness across both nights

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

Night-by-night timing & conditions

Friday

6.3h moonless · Moon 39% lit
Longest moonless stretch: 23:00–05:20

Forecast cloud range: 5–41% at 2 available dark-time samples. Not full-night coverage or a probability.

Saturday

5.7h moonless · Moon 48% lit
Longest moonless stretch: 23:40–05:20

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

Moonless time rank 5

30 Oct – 31 Oct

7.3h moonless / 20.0h astronomical darkness across both nights

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

Night-by-night timing & conditions

Friday

3.0h moonless · Moon 68% lit
Longest moonless stretch: 19:20–22:20

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

Saturday

4.3h moonless · Moon 56% lit
Longest moonless stretch: 19:20–23:40

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

Moonless time rank 6

27 Nov – 28 Nov

5.7h moonless / 21.3h astronomical darkness across both nights

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

Night-by-night timing & conditions

Friday

2.3h moonless · Moon 82% lit
Longest moonless stretch: 19:00–21:20

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

Saturday

3.3h moonless · Moon 72% lit
Longest moonless stretch: 19:00–22:20

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

Moonless time rank 7

20 Nov – 21 Nov

1.7h moonless / 20.7h astronomical darkness across both nights

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

Night-by-night timing & conditions

Friday

1.3h moonless · Moon 87% lit
Longest moonless stretch: 04:00–05:20

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

Saturday

0.3h moonless · Moon 93% lit
Longest moonless stretch: 05:00–05:20

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

Moonless time rank 8

23 Oct – 24 Oct

0.3h moonless / 20.0h astronomical darkness across both nights

October seasonal context
3.6 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 96% lit
Longest moonless stretch: 05:00–05:20

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

Saturday

0.0h moonless · Moon 99% 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 Pacific/Honolulu 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 →