Predict temperature
Logically, when clouds hide the sun, the temperature cools. It is therefore important to provide a warmer clothing so as not to be cold when a cloud appears. Conversely, at night, clouds retain the heat of the earth, so it would be cooler if the sky is clear.
Predict wind direction and speed changes
A changing sky with more, less or different kinds of clouds announces a change of weather. Other signs should also be taken into account, such as a change in the barometer indication, a rapid change in temperature, a change in visibility on the horizon, or sailboats on the horizon lying on a different side of ours. If you can, spot flags or smoke on the coast that change direction under the effect of the wind.
Predicting rain
The darker a cloud is, the more it is saturated with water and therefore a harbinger of rain, it will therefore be necessary to anticipate this change in weather and provide for the watch jacket to protect oneself. The higher the clouds are in the sky, the better the weather. On the other hand, if they get closer to the ground, they are predictors of rain. Finally, the rainbow in the wind announces the arrival of rain and downwind the end of rain.
Forecast wind gusts
Cumuliform clouds predict gusts, and the thicker they are, the stronger and more violent the gusts. Large cumulus clouds and cumulonimbus clouds can cause gusts to over 40 knots. And this change of weather can be very fast, barely 20 minutes! It is therefore imperative and fast to reduce the sail, moor what can take off and equip itself accordingly.
Weather Forecasting
The cirrus, followed by cirrostratus, heralds the arrival of a depression. They are a sign of bad weather, during the day or for the next day. They generate rain and wind that will intensify throughout the day. It is then necessary to inquire about the weather forecast and probably join a shelter.
Dark cumulonimbus clouds approaching the horizon, associated with a drop in barometer values and a change in wind speed (more wind or very light in the direction of dark clouds) are also heralds of stormy weather.
