Did you know bubbles in a hot cup of coffee, tea or cocoa can give you an idea of what the weather is going to be like for the day? Instructables user stickmop shared this trick from Backpacker magazine: pour a cup and watch what happens to the bubbles: if they move to the edge quickly, then there should be clear skies for the next 12 hours; if they stay in the middle it means rain; if they move slowly then you might have some rain but things should clear up soon.
How does it work? Basically, your cup of coffee becomes a very inexpensive barometer – and the movement of the bubbles gives you a rough indication of the air pressure.
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from The UberReview