Hour-by-Hour Stargazing Forecast

Why Timing Matters for Stargazing

A clear sky at 9 PM doesn't guarantee clear skies at midnight. Weather systems move, clouds form and dissipate, and atmospheric conditions shift throughout the night. That's why a snapshot forecast isn't enough — you need to see how conditions evolve hour by hour to plan the best stargazing session.

Starglow's timeline view solves this by laying out every relevant metric across the entire night in a single, scrollable grid. Instead of checking back repeatedly or guessing when clouds might clear, you can see the full picture at once and choose your observing window with confidence.

What the Timeline Shows

The timeline grid packs a lot of information into an easy-to-scan format. Each column represents one hour, and each row tracks a different metric:

Cloud Coverage Rows

The top rows show cloud coverage at each altitude level — total, high, mid, and low. Each cell is color-coded green, amber, or red based on how favorable that hour is for stargazing. You can quickly scan across to find stretches of green — those are your prime observing windows.

Celestial Events

The timeline marks key celestial events: when the Sun sets and rises (defining your available dark window), when the Moon rises and sets (affecting sky brightness), and when the ISS is visible overhead. These markers help you plan around natural light conditions.

Viewing Quality Rating

An overall viewing quality score combines all atmospheric factors into a single color-coded rating for each hour. This is the fastest way to identify the best time to head outside — scan for green hours and you're set.

How to Use the Timeline Effectively

• Scan for green clusters. Look for consecutive hours of green ratings — a 2-3 hour window of clear skies is ideal for a meaningful observing session. Single green hours surrounded by red can be risky since clouds may arrive early.
• Check the Moon row. Even on a clear night, a bright Moon washes out faint objects. The timeline shows you when the Moon is up and when it sets. Deep-sky observers should target hours when the Moon is below the horizon.
• Look for clearing trends. If the early evening shows red (cloudy) but transitions to green after midnight, plan a later session. Many of the best stargazing nights start after the weather clears post-sunset.
• Compare multiple nights. With Starglow Pro's 5-day forecast, you can compare the timeline across several nights and pick the one with the longest, clearest window.
• Coordinate with ISS passes. If there's an ISS pass scheduled, make sure the cloud coverage for that specific hour looks good. No point heading out for a pass if clouds are rolling in at that exact time.

Planning Your Stargazing Session

The best stargazing sessions start with a plan. Here's a simple workflow using the timeline:

1. Open Starglow and check tonight's timeline view.
2. Identify the hours with the lowest cloud coverage and best viewing quality (green cells).
3. Note when the Moon sets — plan your deep-sky observing after moonset for the darkest skies.
4. Check for any ISS passes during your window and factor those in.
5. Set an alarm if the best conditions are late at night, so you don't miss your window.

With Starglow's timeline, you spend less time guessing and more time observing. Every clear hour is accounted for, and you'll always know the best time to look up.