Pressure Tendency Forecast
Reads barometer trend rules and outputs a forecast paragraph in plain English.
Inputs
Result
A natural placement between the calculator and the explanation.
What this solves — and what it doesn't
A barometer you read once tells you the current pressure; a barometer you read over hours tells you the trend. The trend is more informative. Falling pressure with shifting winds and building cumulus is the classic recipe for a storm; rising pressure is the reverse. This tool combines a 3-hour pressure delta with wind shift and cloud trend into a plain-English forecast.
How to read the result
Read the trend (Falling / Rising / Steady) and the magnitude (slow vs rapid). Slow changes (<0.5 hPa / 3hr) mean gradual shifts; rapid changes (>1.5 hPa / 3hr) mean strong systems.
Add the wind and cloud inputs for higher confidence. A clockwise wind shift with falling pressure is textbook cold-front passage.
Limitations
- Doesn’t replace a real forecast. Use this for hour-to-hour decision making between model updates.
- Barometer must be calibrated; altimeter setting matters.
- No model of localized effects (sea breeze, mountain wind).
Frequently asked questions
Do I need a fancy barometer?
No — many watches and phones have barometric pressure. A $15 dial barometer is enough for the trend.
What is a normal range?
~980 to 1040 hPa at sea level. Lower at altitude. Adjust for your elevation.
Is this safe to use for navigation?
No — this is weather trend reading, not navigation.