Here's my own note:
- Check the grass for dew at sunrise. If the grass is dry, this indicates clouds or strong breezes, which can mean rain. If there's dew, it probably won't rain that day.
- Remember the rhyme: "Red sky at night, sailor's delight; Red sky at morning, sailors take warning."If you see a red sky during sunset (west), it means the dry air is heading towards you. A red sky in the morning (East) means that the dry air has passed you, and what follows behind it (on its way towards you) is a low pressure system that carries moisture.
- Look for a rainbow in the west. When a rainbow in the west, it means rain is on its way. On the other hand, a rainbow in the east around sunset means that the rain is on its way out and you can look forward to sunny days.
- Detect which direction the wind is blowing. Easterly winds can indicate an approaching storm front, westerly winds the opposite. Strong winds indicate high pressure differences, which can be a sign of advancing storm fronts.
- Take a deep breath. Close your eyes and smell the air. A proverb says "Flowers smell best just before a rain." Plants release their waste in a low pressure atmosphere, generating a smell and indicating an upcoming rain. Swamps will release gasses just before a storm (because of the lower pressure), which leads to unpleasant smells.
- Check for humidity. Look at the leaves of oak or maple trees. These leaves tend to curl in high humidity, which tends to precede a heavy rain. Pine cone scales remain closed if the humidity is high, but open in dry air. Under humid conditions, wood swells (look out for those sticky doors) and salt clumps.
- Watch the clouds. Clouds going in different directions (e.g. one layer going west, another layer going north) - bad weather coming, probably hail. Cumulonimbus clouds early in the day and developing throughout the day - greater chances of severe weather. Mammatus cloud (formed by sinking air) - can form with both severe and nonsevere thunderstorms as well as other cloud types. Cirrus clouds high in the sky like long streamers - bad weather within the next 36 hours. Altocumulus clouds like mackerel scales - bad weather within the next 36 hours.
- Observe animals. They are more likely to react to changes in air pressure than we are. Animals, especially birds, get very quiet immediately before it rains.
- Make a campfire. The smoke should rise steadily. Smoke that swirls and descends is caused by low pressure (i.e. rain on the way).
- Look at the moon during the night. If it is reddish or pale, dust is in the air. But if the moon is bright and sharply focused, it's probably because low pressure has cleared out the dust, and low pressure means rain. Also, a ring around the moon can indicate that rain will probably fall within the next three days.