Stargazing at Guadarrama National Park: when is the sky clear and dark?
August is the best month for stargazing at Guadarrama National Park: on average 62 clear, moonless hours of full darkness, and 44% of nights have at least two of them (ERA5, 2006–2025). The darkest spot we found there is darker than 43% of Europe’s land (NASA VIIRS 2025).
national park · Spain
Month by month
| Month | Nights with ≥ 2 such hours | Clear moonless dark hours | Moonless dark hours | Of them clear |
|---|---|---|---|---|
| January | 21% | 34 | 179 | 19% |
| February | 27% | 44 | 142 | 31% |
| March | 23% | 35 | 140 | 25% |
| April | 20% | 31 | 112 | 28% |
| May | 24% | 31 | 87 | 36% |
| June | 28% | 31 | 77 | 41% |
| July | 46% | 57 | 87 | 66% |
| August | 44% | 62 | 107 | 58% |
| September | 35% | 56 | 131 | 42% |
| October | 32% | 55 | 155 | 36% |
| November | 22% | 40 | 168 | 24% |
| December | 22% | 44 | 175 | 25% |
Climate, not a forecast: these are shares of past nights (ERA5 reanalysis, 2006–2025), not a prediction for a particular night. Check a forecast before you go.
Light pollution
| Darker than | 43% of Europe’s land |
|---|---|
| Light pollution | noticeable light glow |
| Sky-glow index (own, VIIRS) — Darkest spot we found | 5.13 |
| Sky-glow index (own, VIIRS) — at the official map point | 22 |
| Sky-glow index (own, VIIRS) — median across the area | 15 |
| Darkest spot we found | 41.025, -3.758 (map) — within the OSM boundary |
Next new moons
| New moon | Night | Moonless dark hours that night | Typical share of good nights that month |
|---|---|---|---|
| 9 November 2026 | 8–9 November 2026 | 10.8 | 22% |
| 9 December 2026 | 8–9 December 2026 | 11.3 | 22% |
| 7 January 2027 | 7–8 January 2027 | 11.3 | 21% |
| 6 February 2027 | 6–7 February 2027 | 10.5 | 27% |
| 8 March 2027 | 7–8 March 2027 | 9.3 | 23% |
| 6 April 2027 | 6–7 April 2027 | 7.8 | 20% |
| 6 May 2027 | 5–6 May 2027 | 6.2 | 24% |
| 4 June 2027 | 4–5 June 2027 | 4.8 | 28% |
| 4 July 2027 | 3–4 July 2027 | 4.8 | 46% |
| 2 August 2027 | 1–2 August 2027 | 6.0 | 44% |
| 31 August 2027 | 31 August 2027 – 1 September 2027 | 7.7 | 44% |
| 30 September 2027 | 29–30 September 2027 | 9.0 | 35% |
Hours with the Sun below −18° and the Moon below the horizon, on the night of the new moon, at the darkest spot.
Meteor showers
| Shower | Peak night | Chance of a clear peak night | Moon lit | Moonless dark hours (Sun < −12°) | Radiant max. height |
|---|---|---|---|---|---|
| Leonids | 17–18 November 2026 | 48% | 55% | 6.2 | 70° |
| Geminids * | 13–14 December 2026 | 32% | 20% | 9.7 | 82° |
| Geminids * | 14–15 December 2026 | 30% | 29% | 8.7 | 82° |
| Quadrantids | 3–4 January 2027 | 25% | 13% | 11.2 | 66° |
| Lyrids | 22–23 April 2027 | 32% | 95% | 1.2 | 83° |
| Eta Aquariids * | 5–6 May 2027 | 45% | 0% | 7.5 | 21° |
| Eta Aquariids * | 6–7 May 2027 | 42% | 1% | 7.5 | 22° |
| Perseids * | 12–13 August 2027 | 73% | 84% | 3.0 | 66° |
| Perseids * | 13–14 August 2027 | 78% | 90% | 2.0 | 66° |
| Orionids | 21–22 October 2027 | 43% | 58% | 3.7 | 65° |
| Leonids * | 17–18 November 2027 | 48% | 82% | 2.0 | 70° |
| Leonids * | 18–19 November 2027 | 47% | 72% | 3.3 | 70° |
| Geminids | 14–15 December 2027 | 30% | 98% | 0.0 | 82° |
* The peak falls in daylight in Europe, so both neighbouring nights are shown.
Clear peak night: at least 2 hours with ≤ 20 % cloud while the Sun is below −12°, on the same calendar night ± 1 in 2006–2025.