Dark Sky Quality
Scores forecast sky quality for deep-sky, starscape, and nightscape photography using darkness, moon interference, clouds, atmospheric transparency, precipitation risk, and forecast confidence. This is not a Bortle class or site-darkness/light-pollution rating.
What is Dark Sky Quality?
Technical detailsDark Sky Quality evaluates whether the forecasted sky conditions at a location and hour are favorable for general astrophotography, including deep-sky imaging, star fields, constellations, nightscapes, and meteor sessions. It combines astronomical darkness, Moon altitude and illumination, cloud layers, aerosol and visibility-based transparency, active-weather suppression, and ensemble confidence into a single 0-100% score. This field deliberately measures forecast sky quality, not intrinsic site darkness. It does not estimate Bortle class, skyglow, or light pollution; a dark rural site and a bright urban site can receive the same score if the weather and astronomy forecast are equally favorable. Use it to decide when the sky is likely clear, dark, transparent, and moon-friendly enough to make an astro outing worthwhile.
Photography tip
How to use this conditionMeasures forecast sky quality for astro shooting, not site darkness or Bortle class. Best results combine astronomical darkness, Moon below or dim, low clouds/high clouds, clean transparent air, no precipitation risk, and high clear-sky confidence.
Dark Sky Quality in photography
In depthDark Sky Quality is PhotoWeather's Pro-tier forecast metric for astrophotographers who need more than a simple clear-sky forecast. The score evaluates whether the next hours are likely to be good for deep-sky imaging, star fields, constellations, meteor showers, and nightscape photography by combining the factors that most often make or break an astro session: astronomical darkness, Moon altitude and illumination, total and high cloud cover, visibility, humidity, aerosol optical depth, smoke, dust, sea salt, precipitation risk, and ensemble confidence.
Unlike a Bortle map or light-pollution layer, Dark Sky Quality is not a measure of permanent site darkness. It does not claim that a location is intrinsically dark, rural, or free from skyglow. Instead, it answers a practical forecast question: are the sky and atmosphere at this place and hour likely to be dark, clear, transparent, and reliable enough for astro photography? High scores indicate moon-friendly astronomical darkness with clean air and low cloud risk, while lower scores flag twilight, bright Moon interference, haze, high cloud veils, precipitation, or uncertain cloud forecasts. Photographers can combine this field with their own knowledge of site darkness to choose the best night and hour for taking the astro kit out.
Frequently asked questions
Common questionsWhat is Dark Sky Quality?
Dark Sky Quality evaluates whether the forecasted sky conditions at a location and hour are favorable for general astrophotography, including deep-sky imaging, star fields, constellations, nightscapes, and meteor sessions. It combines astronomical darkness, Moon altitude and illumination, cloud layers, aerosol and visibility-based transparency, active-weather suppression, and ensemble confidence into a single 0-100% score. This field deliberately measures forecast sky quality, not intrinsic site darkness. It does not estimate Bortle class, skyglow, or light pollution; a dark rural site and a bright urban site can receive the same score if the weather and astronomy forecast are equally favorable. Use it to decide when the sky is likely clear, dark, transparent, and moon-friendly enough to make an astro outing worthwhile.
How does Dark Sky Quality affect photography?
Measures forecast sky quality for astro shooting, not site darkness or Bortle class. Best results combine astronomical darkness, Moon below or dim, low clouds/high clouds, clean transparent air, no precipitation risk, and high clear-sky confidence.
What values are typical for Dark Sky Quality?
Dark Sky Quality typically ranges from 0.0% to 100.0%. PhotoWeather monitors these values to help you identify ideal conditions for your photography goals.
How is Dark Sky Quality calculated?
Dark Sky Quality is an advanced derived condition calculated from multiple weather parameters including Solar Elevation, Moon Altitude, Moon Illumination, Total Cloud Coverage, Low Clouds. PhotoWeather's algorithms analyze these factors to provide a single, easy-to-understand score for this photography opportunity.
Typical values
Value rangeRelated fields
Similar weather conditionsAurora Quality
Combines aurora activity with viewing conditions (darkness, cloud cover, visibility) to provide photography-ready aurora quality scores. Aurora activity is OVATION-aware from the compute step.
Blue Hour Quality
Evaluates atmospheric conditions for blue hour photography quality. Scores sky clarity, cloud type suitability (high thin clouds ideal), visibility, and calm conditions.
Fiery Red Sky Potential
Predicts the chance of vivid red, orange, and pink sunrise or sunset color. Best when the sun has a clear opening near the horizon, some clouds are ready to catch the light, and low clouds are not blocking the show.
Fog Probability
How likely fog is to form. High scores mean misty, atmospheric conditions for moody landscape and sunrise photography.
Golden Hour Potential
Atmospheric suitability for golden hour photography across extended time window around golden hour periods
Golden Clouds Potential
Cloud formation suitability for golden hour photography across extended time window around golden hour periods
Cloud Drama Score
Analysis of cloud formations and atmospheric conditions for dramatic sky photography
Storm Intensity
Storm intensity analysis combining precipitation, wind conditions, atmospheric pressure, visibility, GFS simulated radar reflectivity, and wind shear for enhanced storm organization detection.
Frost Probability
Frost formation probability combining temperature, dewpoint spread, cloud cover, and wind analysis
Dew Probability
Dew formation probability combining overnight radiative cooling, surface temperature, moisture, and wind analysis
Rainbow Probability
Probability of visible rainbow formation based on solar geometry and precipitation patterns
Coastal Drama Score
Analysis of coastal conditions combining wave dynamics, atmospheric conditions, and lighting for dramatic seascape photography. Evaluates wave height, swell patterns, spray potential, and atmospheric drama factors.
Atmospheric Clarity Score
Comprehensive atmospheric clarity analysis for landscape and astrophotography using CAMS aerosol optical depth, particle composition (dust, smoke, sea salt), particle size distribution (Ångström exponent), and visibility conditions.
Milky Way Possibility
Scores Milky Way core / Galactic Center shootability using Galactic Center altitude plus dark, clear, transparent, moon-friendly forecast sky conditions. This is not a generic Milky Way band detector or site-darkness rating.
Light Breakthrough Potential
Likelihood of sun breaking through clouds creating dramatic rays and dappled light patterns. Best with partial cloud cover (40-70%) and some sunshine reaching the surface.
Soft Light Index
Quality of diffused light for portrait and product photography. High scores indicate soft, even lighting that minimizes harsh shadows - the 'giant softbox' effect.
Cloud Texture Score
Rates how visually interesting the clouds are - distinguishing dramatic formations from boring flat overcast. High scores indicate structured clouds with good light transmission.
Overcast Flatness
How flat and boring the overcast is. HIGH scores indicate uniform gray sky with no breaks or texture - generally unfavorable for most photography. LOW scores indicate breaks, texture, or clearing.
Moon Altitude
Moon's elevation angle above horizon
Moon Illumination
Percentage of moon disc illuminated (0% = new, 100% = full)
Total Cloud Coverage
Overall cloud coverage across all altitudes
High Clouds
Cloud coverage above 6km altitude (cirrus)
Aerosol Optical Depth (550nm)
Total aerosol optical depth at 550nm. Lower values indicate clearer skies and more vivid colours.
Smoke AOD (550nm)
Smoke component of aerosol optical depth (black carbon + organic matter). Indicates wildfire smoke or urban pollution affecting air quality and visibility.
Visibility
Horizontal visibility distance
Clear Sky Probability (Ensemble)
Probability of clear sky based on GEFS ensemble (TCDC < 30%)
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