StarCast · Astrophotography Conditions
LightCast

Astrophotography
Weather Forecast Tonight

"Clear" isn't good enough for astrophotography. StarCast checks moon phase, cloud at every layer, Bortle class, and transparency — and gives you one number.

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Tonight's checklist

Five Things That Have to Be Right

Standard forecasts tell you temperature and cloud percentage. Neither is what astrophotography actually needs. StarCast checks the five variables that actually determine whether tonight is worth driving out for.

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Moon Phase
New moon ±5 days. Anything brighter than a crescent significantly washes out the Milky Way and deep sky objects. Check moon illumination percentage, not just phase name.
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Cloud — All Three Layers
Low, mid, and high cloud checked separately. Thin cirrus at high altitude is invisible from the ground but measurably reduces astrophotography contrast.
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Bortle Class
Bortle 4 or lower for the Milky Way. Bortle 3 or lower for serious deep sky work. Your location's class is fixed — but knowing it saves you from driving to a spot that was never going to work.
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Atmospheric Transparency
Humidity, smoke, and aerosols create a veil even on cloud-free nights. Post-cold-front air is the cleanest of any given week. StarCast scores transparency separately from cloud cover.
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Season
Milky Way core season in the Northern Hemisphere: February through October, peak May through August. Outside that window, the core is below the horizon during nighttime hours.
LightCast StarCast astrophotography conditions score
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Plan shoots days in advance
The LightCast iOS app shows a multi-day StarCast forecast and sends a push notification when an upcoming night hits your threshold. Plan around the new moon window without checking manually every evening.
Common Questions
What is the best weather forecast app for astrophotography?
LightCast StarCast is built specifically for astrophotography. It scores conditions using moon phase, cloud at all layers, Bortle class, and atmospheric transparency. Free at lightcastsuite.com/starcast, with push notifications in the iOS app.
How do I check if tonight is good for astrophotography?
Start with moon phase — if it's more than half full, the night is already compromised. Then check all cloud layers, not just total percentage. Then confirm your location's Bortle class. StarCast checks all three automatically.
Why does my astrophotography look hazy on clear nights?
Atmospheric transparency. High humidity, smoke, and aerosols scatter light and reduce contrast even when the sky appears cloud-free. Post-rain air after a cold front is the cleanest of any given week. StarCast scores transparency separately from cloud cover.
How do I plan astrophotography shoots in advance?
Build around the new moon calendar first — 5 days before to 5 days after new moon is your window each month. Then check the multi-day forecast for clear nights within that window. The LightCast iOS app lets you see the full week forecast and set push notifications so you're not checking manually every night.
LightCast
Five conditions. One score. Go or don't.

Moon phase & timing · Cloud at all layers · Bortle class
Atmospheric transparency · Push notifications · Saved locations

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