Eight-week planning horizon

Choose your observing weekend

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

Bright sky

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

18.4–19.1 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 / 23.3h astronomical darkness across both nights

December 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

10.3h moonless · Moon 12% lit
Longest moonless stretch: 18:20–04:40

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

Saturday

11.7h moonless · Moon 7% 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

21.3h moonless / 21.3h astronomical darkness across both nights

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

Night-by-night timing & conditions

Friday

10.7h moonless · Moon 4% lit
Longest moonless stretch: 18:40–05:20

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

Saturday

10.7h moonless · Moon 1% lit
Longest moonless stretch: 18:40–05:20

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

Moonless time rank 3

13 Nov – 14 Nov

18.3h moonless / 22.0h astronomical darkness across both nights

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

Night-by-night timing & conditions

Friday

9.7h moonless · Moon 22% lit
Longest moonless stretch: 20:00–05:40

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

Saturday

8.7h moonless · Moon 31% lit
Longest moonless stretch: 21:00–05:40

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

Moonless time rank 4

16 Oct – 17 Oct

15.0h moonless / 19.3h astronomical darkness across both nights

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

Night-by-night timing & conditions

Friday

8.0h moonless · Moon 38% lit
Longest moonless stretch: 22:00–06:00

Forecast cloud range: 75–100% at 2 available dark-time samples. Not full-night coverage or a probability.

Saturday

7.0h moonless · Moon 47% lit
Longest moonless stretch: 23:00–06:00

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

Moonless time rank 5

30 Oct – 31 Oct

5.0h moonless / 21.3h astronomical darkness across both nights

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

Night-by-night timing & conditions

Friday

1.7h moonless · Moon 69% lit
Longest moonless stretch: 19:40–21:20

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

Saturday

3.3h moonless · Moon 58% lit
Longest moonless stretch: 19:40–23:00

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

Moonless time rank 6

27 Nov – 28 Nov

3.7h moonless / 23.3h astronomical darkness across both nights

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

Night-by-night timing & conditions

Friday

1.0h moonless · Moon 82% lit
Longest moonless stretch: 18:20–19:20

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

Saturday

2.7h moonless · Moon 73% lit
Longest moonless stretch: 18:20–21:00

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

Moonless time rank 7

20 Nov – 21 Nov

1.7h moonless / 22.7h astronomical darkness across both nights

November seasonal context
2.3 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 86% lit
Longest moonless stretch: 04:20–05:40

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

Saturday

0.3h moonless · Moon 93% lit
Longest moonless stretch: 05:20–05:40

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

No moonless darkness

23 Oct – 24 Oct

0.0h moonless / 20.0h astronomical darkness across both nights

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

Night-by-night timing & conditions

Friday

0.0h moonless · Moon 95% lit
No moonless dark window

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 America/Los_Angeles 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 →