How to Read a Meteogram: Launch Window, Wind by Altitude and Clouds
A meteogram shows the flying weather at one launch site over several days. Here’s how to read the launch window, wind barbs, working height and weather symbols.
The map shows one moment for many places. The meteogram shows one place over many hours. Open it by tapping a launch site or clicking anywhere on the map.
The launch window at the top
The coloured strip sums up each hour in one verdict: good (green), marginal (yellow) or unsuitable (red). It weighs wind speed, gusts, wind direction against the launch’s approved directions, rain and thunderstorms. The worse partial verdict wins: a site with perfect wind but a thunderstorm risk stays red.
The rating uses fixed limits that know nothing about your skills. A green window means “the model sees no reason against it” — not “right for you”.
Wind barbs by altitude
The chart stacks wind barbs for several altitudes. Colour shows strength: under 10 km/h, under 20, under 30, under 45 and above. Hover over a barb to see exact speed and direction.
Look out for two patterns:
- Wind increasing sharply with height — calm at launch, strong at ridge height: expect turbulence and drifting thermals, rotors in the lee.
- Wind turning with height — if the wind aloft comes from a different direction than at the ground, the slope may sit in the lee of the upper wind even though the surface wind looks fine.
The shaded areas
- Green — usable working height: thermals carry you up to here.
- White — cumulus, from the base up to the thermal top.
- Light blue — air up to condensation. On blue days that’s the height that exists but you won’t get.
- Grey — cloud cover; a lot of it shades the ground and dampens thermals.
- Bands at the bottom — the terrain in schematic altitude zones from valley to rock.
- Orange line — the climb rate w*.
Weather symbols
Cloud symbols show cloud cover, drops show precipitation with the amount in mm/h (from 0.1 mm/h). A lightning bolt appears from a CAPE of 800 J/kg — from there the air mass is unstable enough for thunderstorms. More in the thunderstorm article.
Putting it to use
- Search for or tap a launch site and pick the day at the top.
- Find the green launch window — and check it lines up with a good working height.
- Look at the barbs at ridge height: does the upper wind fit too?
- Look to the right: is there lightning or rain in the afternoon? Then plan to land before it.