Dark Sky Odds

Stargazing at Bory Tucholskie National Park: when is the sky clear and dark?

March is the best month for stargazing at Bory Tucholskie National Park: on average 32 clear, moonless hours of full darkness, and 21% of nights have at least two of them (ERA5, 2006–2025). The darkest spot we found there is darker than 67% of Europe’s land (NASA VIIRS 2025).

Data updated: 31 December 2025 · Sources and licences

Calculated 5 November 2026 · cloud cover ERA5 2006–2025 · night lights NASA VIIRS 2025

national park · Poland

MarchBest month
193Clear moonless dark hours a year
67%darker than … of Europe’s land
21%Nights with ≥ 2 such hours (March)

Month by month

MonthNights with ≥ 2 such hoursClear moonless dark hoursMoonless dark hoursOf them clear
January9%151778%
February14%1914613%
March21%3212725%
April22%267833%
May3%41133%
June0%00—
July0%00—
August13%166126%
September21%3011227%
October16%2415216%
November10%141768%
December8%131897%

No astronomical darkness (June, July): the Sun stays above −18° all night.

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 than67% of Europe’s land
Light pollutiondark rural sky (darkest 20–50 %)
Sky-glow index (own, VIIRS) — Darkest spot we found1.55
Sky-glow index (own, VIIRS) — at the official map point2.37
Sky-glow index (own, VIIRS) — median across the area1.92
Darkest spot we found53.842, 17.542 (map) — within the OSM boundary

Next new moons

New moonNightMoonless dark hours that nightTypical share of good nights that month
9 November 20268–9 November 202611.010%
9 December 20268–9 December 202612.08%
7 January 20277–8 January 202712.09%
6 February 20276–7 February 202710.714%
8 March 20277–8 March 20278.821%
6 April 20276–7 April 20276.222%
6 May 20276–7 May 20272.33%
4 June 20274–5 June 20270.00%
4 July 20273–4 July 20270.00%
2 August 20271–2 August 20271.013%
31 August 202731 August 2027 – 1 September 20275.813%
30 September 202729–30 September 20278.321%

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

ShowerPeak nightChance of a clear peak nightMoon litMoonless dark hours (Sun < −12°)Radiant max. height
Leonids17–18 November 202617%55%6.858°
Geminids *13–14 December 202615%20%11.069°
Geminids *14–15 December 202613%28%9.869°
Quadrantids3–4 January 202723%13%12.873°
Lyrids22–23 April 202757%95%1.368°
Eta Aquariids *5–6 May 202745%0%5.37°
Eta Aquariids *6–7 May 202750%0%5.28°
Perseids *12–13 August 202733%84%3.265°
Perseids *13–14 August 202742%90%2.367°
Orionids21–22 October 202722%59%2.752°
Leonids *17–18 November 202717%82%1.258°
Leonids *18–19 November 202717%73%2.758°
Geminids14–15 December 202713%98%0.069°

* 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.

How we calculate