# Clear Sky Map for Stargazing Canonical page: https://lightpollutionmap.app/clear-sky-map/ Updated: 2026-07-13 ## Summary The clear-sky map adds long-term climate context to the Light Pollution Map. It helps users compare broad regions and months by the historical share of clear nights. It is a screening tool for destination and season research, not a forecast for a specific night. The interactive layer provides an annual view and twelve monthly views. Colored bands run from red to green. Greener bands indicate a higher historical share of clear nights, while redder bands indicate a lower share. Gray marks lower-confidence coverage and should not be interpreted as always cloudy. Interactive map: https://lightpollutionmap.app/?layer=clearsky&period=annual Localized HTML: 22 languages are available from the guide's language selector. ## What the map represents The layer is produced from multiple years of historical data. Its purpose is to reveal broad and persistent seasonal patterns that are difficult to judge from one forecast or one unusual year. The public map intentionally shows broad ranges rather than exact web grid values. This makes the signal useful for comparison without implying precision that the underlying evidence cannot support everywhere. The map does not claim that every night within a green area will be clear. It also does not claim that red areas cannot produce excellent observing nights. A climate range describes relative historical tendency, not certainty. ## Method and proprietary boundary Light Pollution Map publishes enough information for users to judge the layer's purpose and limits: - It is based on multi-year historical data. - It represents climate ranges, not a future forecast. - Confidence is shown as part of the visual result. - The annual and monthly views support different planning horizons. - Local terrain and current atmospheric conditions can differ from the broad layer. The detailed production process remains proprietary. Source weighting, quality thresholds, cleaning rules, gap handling, grid resolution, and production code are not published. The public layer exposes broad bands and confidence treatment instead of the internal recipe or exact data grid. ## Confidence and limitations Gray areas indicate that the available evidence is less complete or less consistent. Gray is an uncertainty marker. It is not a numeric band and should not be ranked against the colored areas. A broad global layer cannot resolve every local effect. Mountains, valleys, coastal fog, smoke, dust, humidity, terrain shadows, and rapidly changing weather can all change the result at an observing site. The map should be combined with local knowledge and a current forecast. ## How to use the clear-sky layer 1. Start with the annual layer. Compare broad destinations that are also dark enough for your observing goal. 2. Switch to individual months. Look for seasons that improve the clear-night climate while still providing enough darkness for the target. 3. Check nearby months. Climate changes do not begin and end on calendar boundaries. 4. Choose more than one candidate site or date when possible. 5. In the final days, verify cloud, humidity, wind, visibility, smoke, moonlight, access, and safety. ## Climate map versus forecast The clear-sky climate layer answers: Which regions and months have historically offered better clear-night odds? A short-range forecast answers: What are cloud, humidity, wind, and visibility likely to be on a specific upcoming date? An on-site check answers: What is happening at the exact observing location now? These are different stages of one planning process. The climate layer is useful months ahead. A forecast becomes important in the final days. The on-site check is the last decision before observing. ## Annual and monthly views Use the annual view to shortlist regions without overreacting to one season. Use a monthly view when dates are constrained or seasonal weather dominates the choice. There is no universal best month for stargazing. Clear-night climate must be combined with night length, light pollution, moonlight, target visibility, access, and current weather. Planning guide: https://lightpollutionmap.app/best-months-for-stargazing/ ## App handoff On supported mobile devices, the clear-sky panel can open the current map center in StargazingHub for location-specific planning. The current App handoff preserves the selected location and opens the astronomy-planning map. It does not yet transfer the selected month, so the website does not claim that the entire period context is synchronized. The analytics event records the platform, selected period, and entry type. It does not include raw coordinates. StargazingHub: https://stargazinghub.com/ ## Frequently asked questions ### Is this a weather forecast? No. It summarizes multi-year historical climate patterns in broad ranges. Use a current forecast for a particular night. ### What does gray mean? Gray marks lower-confidence coverage. It is an uncertainty signal, not a claim that the location is always cloudy. ### Why can a local forecast look different? The climate map is broad and historical. Local tools can use a more precise point and newer conditions, so differences are expected. ### Can users compare individual months? Yes. Enable the clear-sky layer and choose Year or any month from the legend panel.