{"assessment":{"best_window":null,"cost":{"altitude":0.0,"clouds":9.3,"darkness":2.52,"moon":0.1},"formula":"astronomy = 100 * min(1, sky_hours / reference_hours) * peak_sky; overall = astronomy * score_weather / 100 (null when the weather is unknown)","hard_limit":"Overcast (\u226580 % cloud) for 10.8 of 10.8 dark hours \u2014 the sky is closed whatever the geometry says.","headline":"Not tonight","hourly":[{"alt":null,"cloud":99,"high":0,"iso":"2026-03-21T17:00Z","label":"unusable","low":99,"mid":41,"moon_alt":28,"precip":0.0,"q":0.0,"rh":94,"sky":"civil twilight","temp":-4.4,"time":"19:00","wind":9.6},{"alt":null,"cloud":94,"high":0,"iso":"2026-03-21T18:00Z","label":"unusable","low":87,"mid":56,"moon_alt":18,"precip":0.0,"q":0.0,"rh":93,"sky":"astronomical twilight","temp":-3.6,"time":"20:00","wind":10.1},{"alt":null,"cloud":99,"high":0,"iso":"2026-03-21T19:00Z","label":"unusable","low":98,"mid":71,"moon_alt":7,"precip":0.0,"q":0.0,"rh":96,"sky":"night","temp":-4.3,"time":"21:00","wind":10.0},{"alt":null,"cloud":100,"high":0,"iso":"2026-03-21T20:00Z","label":"unusable","low":100,"mid":76,"moon_alt":-3,"precip":0.0,"q":0.0,"rh":97,"sky":"night","temp":-4.2,"time":"22:00","wind":10.1},{"alt":null,"cloud":100,"high":0,"iso":"2026-03-21T21:00Z","label":"unusable","low":100,"mid":95,"moon_alt":-12,"precip":0.0,"q":0.0,"rh":96,"sky":"night","temp":-3.6,"time":"23:00","wind":8.4},{"alt":null,"cloud":100,"high":0,"iso":"2026-03-21T22:00Z","label":"unusable","low":100,"mid":74,"moon_alt":-19,"precip":0.1,"q":0.0,"rh":97,"sky":"night","temp":-3.4,"time":"00:00","wind":8.7},{"alt":null,"cloud":100,"high":0,"iso":"2026-03-21T23:00Z","label":"unusable","low":100,"mid":99,"moon_alt":-25,"precip":0.0,"q":0.0,"rh":97,"sky":"night","temp":-3.4,"time":"01:00","wind":8.5},{"alt":null,"cloud":100,"high":0,"iso":"2026-03-22T00:00Z","label":"unusable","low":100,"mid":32,"moon_alt":-29,"precip":0.0,"q":0.0,"rh":98,"sky":"night","temp":-3.4,"time":"02:00","wind":8.6},{"alt":null,"cloud":100,"high":1,"iso":"2026-03-22T01:00Z","label":"unusable","low":100,"mid":33,"moon_alt":-30,"precip":0.1,"q":0.0,"rh":98,"sky":"night","temp":-3.5,"time":"03:00","wind":7.8},{"alt":null,"cloud":100,"high":34,"iso":"2026-03-22T02:00Z","label":"unusable","low":100,"mid":13,"moon_alt":-27,"precip":0.1,"q":0.0,"rh":96,"sky":"night","temp":-3.3,"time":"04:00","wind":8.4},{"alt":null,"cloud":100,"high":77,"iso":"2026-03-22T03:00Z","label":"unusable","low":100,"mid":27,"moon_alt":-23,"precip":0.2,"q":0.0,"rh":95,"sky":"astronomical twilight","temp":-3.2,"time":"05:00","wind":8.1},{"alt":null,"cloud":100,"high":9,"iso":"2026-03-22T04:00Z","label":"unusable","low":100,"mid":55,"moon_alt":-16,"precip":0.2,"q":0.0,"rh":98,"sky":"civil twilight","temp":-3.4,"time":"06:00","wind":7.6}],"peak_quality":0.0,"peak_sky":1.0,"quality_hours":0.0,"reasons":["cloud cover cost 9.3 quality-hours","daylight and twilight cost 2.5 quality-hours"],"reference_hours":4.0,"score":0,"score_astronomy":100,"score_weather":0,"sky_hours":9.3,"verdict":"unusable","verdict_astronomy":"good","weather_known":true,"windows":[{"end":"2026-03-22T04:25Z","end_local":"06:25","hours":11.92,"label":"unusable","mean_quality":0.0,"start":"2026-03-21T16:30Z","start_local":"18:30"}]},"calculation_version":"2026-10-10.1","forecast":[{"cloud":94,"dark":false,"high":0,"local":"18:00","low":91,"mid":31,"precip":0.0,"rh":80,"temp":-2.7,"time":"2026-03-21T16:00Z","wind":13.2},{"cloud":99,"dark":false,"high":0,"local":"19:00","low":99,"mid":41,"precip":0.0,"rh":94,"temp":-4.4,"time":"2026-03-21T17:00Z","wind":9.6},{"cloud":94,"dark":false,"high":0,"local":"20:00","low":87,"mid":56,"precip":0.0,"rh":93,"temp":-3.6,"time":"2026-03-21T18:00Z","wind":10.1},{"cloud":99,"dark":true,"high":0,"local":"21:00","low":98,"mid":71,"precip":0.0,"rh":96,"temp":-4.3,"time":"2026-03-21T19:00Z","wind":10.0},{"cloud":100,"dark":true,"high":0,"local":"22:00","low":100,"mid":76,"precip":0.0,"rh":97,"temp":-4.2,"time":"2026-03-21T20:00Z","wind":10.1},{"cloud":100,"dark":true,"high":0,"local":"23:00","low":100,"mid":95,"precip":0.0,"rh":96,"temp":-3.6,"time":"2026-03-21T21:00Z","wind":8.4},{"cloud":100,"dark":true,"high":0,"local":"00:00","low":100,"mid":74,"precip":0.1,"rh":97,"temp":-3.4,"time":"2026-03-21T22:00Z","wind":8.7},{"cloud":100,"dark":true,"high":0,"local":"01:00","low":100,"mid":99,"precip":0.0,"rh":97,"temp":-3.4,"time":"2026-03-21T23:00Z","wind":8.5},{"cloud":100,"dark":true,"high":0,"local":"02:00","low":100,"mid":32,"precip":0.0,"rh":98,"temp":-3.4,"time":"2026-03-22T00:00Z","wind":8.6},{"cloud":100,"dark":true,"high":1,"local":"03:00","low":100,"mid":33,"precip":0.1,"rh":98,"temp":-3.5,"time":"2026-03-22T01:00Z","wind":7.8},{"cloud":100,"dark":true,"high":34,"local":"04:00","low":100,"mid":13,"precip":0.1,"rh":96,"temp":-3.3,"time":"2026-03-22T02:00Z","wind":8.4},{"cloud":100,"dark":false,"high":77,"local":"05:00","low":100,"mid":27,"precip":0.2,"rh":95,"temp":-3.2,"time":"2026-03-22T03:00Z","wind":8.1},{"cloud":100,"dark":false,"high":9,"local":"06:00","low":100,"mid":55,"precip":0.2,"rh":98,"temp":-3.4,"time":"2026-03-22T04:00Z","wind":7.6},{"cloud":100,"dark":false,"high":2,"local":"07:00","low":100,"mid":82,"precip":0.1,"rh":98,"temp":-3.2,"time":"2026-03-22T05:00Z","wind":9.0}],"forecast_source":"history","forecast_updated_at":"2026-10-15T22:43:49Z","limits":{"good_alt":30.0,"usable_alt":20.0},"night":{"dark_from":"2026-03-21T18:07:41Z","dark_hours":8.67,"dark_to":"2026-03-22T02:47:54Z","moon":{"illumination":0.109,"phase":"waxing crescent","waxing":true},"moon_free_dark_hours":7.07,"moonrise":"2026-03-22T05:50:33Z","moonset":"2026-03-21T19:42:14Z","sunrise":"2026-03-22T04:21:19Z","sunset":"2026-03-21T16:34:08Z","twilight":{"astronomical":{"end":"2026-03-21T18:07:41Z","start":"2026-03-22T02:47:54Z"},"civil":{"end":"2026-03-21T17:01:54Z","start":"2026-03-22T03:53:36Z"},"nautical":{"end":"2026-03-21T17:34:27Z","start":"2026-03-22T03:21:06Z"}},"window_end":"2026-03-22T10:00:00Z","window_start":"2026-03-21T10:00:00Z"},"night_date":"2026-03-21","site":{"elev_m":1750,"lat":41.693,"lon":24.739,"name":"NAO Rozhen"},"warnings":[]}