The beautiful and sometimes foreboding colors of the sky carry a wealth of information about the weather. For years, sailors have relied on the sky's color to predict the weather, with sayings like, "Red sky at night, sailor's delight; red sky at morning, sailors take warning."
Begin with your intuition. A sky darkened by large, rolling clouds is a very reliable sign of rain or thunderstorms ahead. Often, larger cloud formations create a prematurely darkened sky of a dark blue, gray and charcoal color. Your natural instinct will tell you some kind of heavy weather is coming, and you will most likely be right.
Use the old proverbs. Every sailor is familiar with the "Red sky at night sailor's delight..." proverb. These proverbs have some scientific basis. In the case of the red sky, weather systems that move west to east filter sunlight through their clouds, causing the western sky to illuminate red (or orange or pink) as the storm recedes at sunset. The red eastern sky in the morning is an indicator that storm system are approaching from the east.
Look for exotic colors. Like the red sky, green, blue, purple and orange colors in the sky also indicate the presence of particles in the atmosphere, often caused by weather systems and cloud formations. The color of the sky is determined in large part by the time of day, since the angle of sunlight's refraction against the cloud creates a different color. So, use the location of the color in the sky and the prevailing wind direction to predict where weather is coming from and when.
Pay attention to clarity and hue. Fog is one of the other great indicators of weather that frequently manifests in color. A summertime fog produces dull, hazy yellows in the sky. Take summer fog as a sign of good weather for the next day. Winter fog, on the other hand, indicates the meeting of air currents of different humidity, which often brings rain.