Read the forecast.
Then look up.

1. Check the place and both times

Use the location where you plan to observe, not a saved example city. Check the valid time, meaning when the forecast applies, separately from the updated time, meaning when the provider refreshed its forecast data.

A newly updated forecast can still describe tomorrow rather than tonight. If a time is labelled UTC, compare it with your local time before making plans. MET Norway’s forecast format distinguishes update metadata from forecast timestamps, which are in UTC.

2. Read the values, not just a colour

• Cloud cover: forecast cloud cover is not the probability that you will see your chosen target.
• Wind and temperature: check the units and prepare for the outdoor conditions. A value in metres per second is not the same number in kilometres per hour.
• Humidity: this is a separate forecast value, not a replacement for a telescope’s view or a promise of clear skies.
• Missing values: “unavailable” does not mean zero cloud, no wind or perfect conditions. Look for another current source rather than treating missing data as favourable weather.

These are forecasts, not observations at your exact observing spot. Recheck local conditions and official warnings before travelling.

3. Keep an observing score in perspective

An app may combine cloud, wind, humidity and Moon information into an observing score. Unless its meaning and calibration are explicitly explained, do not read “80/100” as an 80% chance of seeing an object. Check the underlying values and the forecast’s location and time.

Weather alone cannot measure the view past a nearby building, the light pollution around you or whether a faint object needs equipment. Moonlight also affects faint targets. NASA’s observing-location guide explains these separate considerations.

4. Know when to use another source

If a forecast has no source, no time, an unexpected location or missing values, avoid making a travel decision from its score. A current forecast may not cover a historical time-travel view, and a provider may not supply the future date you selected.

A “best observing window” needs supporting forecast information. A fixed time range or a clock-based estimate is not enough to predict a clear interval. For your first session, combine a current weather forecast with our beginner’s checklist.

5. Check weather-data privacy

A direct weather request can send the chosen coordinates to a provider and reveal the requesting device’s IP address. Check your app version, the displayed provider and the published app privacy information; this guide does not replace that policy.

MET Norway’s API terms describe coordinate and IP logging for direct requests. Its privacy statement says unauthenticated meteorological services retain IP addresses for up to 90 days. Open-Meteo’s privacy information describes API logs that can include coordinates and are deleted after 90 days. A provider link is not a claim that every AstraScope version uses that provider.

This website makes no weather API calls. Opening a provider’s link takes you to that provider’s website and its own privacy practices.