You don't need a barometer to predict the weather. Careful observation can be just as effective.
Step 1: Watch the clouds Watch the clouds. If there is cloud cover on a winter night, the next day will be warm because the clouds will trap the heat of the previous day. If clouds are moving in opposite directions to each other, expect bad weather. Dark clouds often indicate upcoming rain.
Step 2: Monitor the humidity Look for signs of increasing humidity in curling leaves on trees and in front doors that stick due to swelling of the wood.
TIP: If your hair is sensitive to changes in humidity, you have the natural gift of weather forecasting.
Step 3: Watch animals Watch animals. Birds often take flight when they expect fair weather. Cows like to lie down when a storm is coming, and ants build up their hills just before rain comes.
Step 4: Check the air conditions Check the air conditions. If the air smells like a compost pile, expect rain. Plants release their waste when the pressure drops, releasing the smell.
Step 5: Check the wind Check the wind. Strong winds indicate high pressure differences and may be a sign that a storm is coming. If your observations indicate a storm brewing, you should probably go run for shelter now!
FACT: The mercury barometer, which measures air pressure, was invented in 1643 and its basic principles are still used in modern barometers.