Xasteria brings the Astronomical-oriented ASTRO weather forecast of the service 7Timer! to your iOS device. You can use your device GPS for a forecast of your location, or enter manual coordinates.
Additional weather sources are offered: Clear Sky Charts (for North American users), as well as quick access to web sources like Clear Outside, Meteoblue, Windy, the latest water vapor satellite images and even light pollution maps.
ISS and bight satellite passes for your location are also shown (data from

7Timer! is mainly derived from the NOAA/NCEP-based numeric weather model, the Global Forecast System (GFS) and gives you a forecast for the entire globe with a resolution of about 20km at 3-hour intervals.

The data provided includes:
-Sun/Moon rise/set & twilight times.
-Moon phase.
-Cloud cover.
-Astronomical seeing.
-Atmospheric transparency.
-Atmospheric instability.

Xasteria provides you with a choice of 3 visualization modes for the data: the new 7Timer! ASTRO graphics, the color-stripe graphics similar to some other astro-forecast services and a raw text mode.

Xasteria is available in English, Greek and French. If you would like to translate it to your own language, please contact the author.

Xasteria will always be ad-free. If you would like to support it, as well as fund the 7Timer! service behind it, you can get Xasteria Plus, which can access non-free weather sources and has some extra features like night vision mode, a lunar calendar and a location manager.

I would appreciate a quick review on iTunes if you are using the app - if you have a specific request/suggestion you can also try the official app page at

What’s New

Version 3.2

Why not help out by rating or reviewing the new version! There are never popups inside the app to ask you (annoying!), which leads to less reviews than other apps.
Here's what's new:
- Light pollution button with Bortle class & WA2015 color code display, that opens a light pollution details page.
- Added, Astrospheric, Jetstream forecast to "Other" sources.
- Decimal coordinates switched to lat, lon to match popular (Google maps etc) usage.
- Clicking the bottom bar in ISS/Satellite tools opens the relevant Havens Above page.

Ratings and Reviews

4.8 out of 5
33 Ratings

33 Ratings

GKth ,

Great App

Extremely useful in planning observing sessions with all weather-related information I need presented in clean, straight-forward manner. Also like the added “alternative forecasts” feature that makes the NOAA satellite service and Clear Outside weather applications available. Recently I needed information for several areas on the US west coast plus several towns along the western Mexican coast but after my trip they were still listed in the app but no longer needed. Sent a note to Dimitrios asking if he could add a feature whereby unwanted locations could be removed. He actually put that in the latest revision and then sent me a note letting me know that that feature I requested was now available!

PaplooTheLearned ,

My Go-To App for Astro Weather

This is always the first app (and often the only app) I check to plan what nights I should pull out my telescope.

It does a brilliant job of making it easy to see astronomically related forecast data from a variety of sources (some of which have no mobile apps), allowing me to easily compare to see what the forecast really looks like.

NeoObserver ,

Favorite app to plan observing

Xasteria has become my go to app to plan observing sessions. Over the last three years it has continued to improve so that I now turn to it first. The improvements I value most are improvement of its weather prediction, incorporation of link outs to other prediction models and several smaller usability improvements.


Dimitrios Kechagias
7.1 MB

Requires iOS 9.0 or later. Compatible with iPhone, iPad, and iPod touch.


English, French, Greek

Age Rating


  • Family Sharing

    With Family Sharing set up, up to six family members can use this app.

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