Pre-flight Weather Check: Reading Wind, Clouds, and Thermals

The most important decision in flying is made "before takeoff." Far more often than skill, weather judgment determines safety.

Wind

• Wind speed: the more of a beginner you are, the lighter the wind you fly in. As wind speed approaches your glider's forward speed, making headway gets hard and there's a risk of going backward.
• Wind direction: a safe takeoff requires the wind to meet the launch head-on. Crosswind and tailwind are dangerous.
• Gusts: more than the average wind speed, the peak gust and the range of variation matter.

Reading clouds

• Cumulus (puffy clouds): moderate cumulus is a good sign of rising air (thermals) beneath it.
• Overdevelopment / cumulonimbus (CB): if clouds develop vertically and rapidly, there's a risk of strong lift and sink, gusts, and thunderstorms. This is a no-fly signal.
• Cloud base: keep margin so you aren't sucked up past the base of the clouds.

Thermals and timing

Thermals (rising columns of warm air) form as the ground heats up and usually strengthen around midday. For beginners, calm periods with weak thermals are safer. (Intro to thermalling and cross-country)

When in doubt, hold off

When conditions are ambiguous, not flying is always the right call. Another chance to fly will come, but the price of an overreach is hard to recover from.

This article is for general information; conditions differ by region, season, and launch. Always follow the judgment of local instructors and veteran pilots.