Pressure
The atmosphere's weight — and its forecast hints
What is it?
Sea-level pressure is the weight of the air column above you, normalized to sea level. Its absolute value matters less than its trend: falling pressure signals approaching low-pressure systems and unsettled weather; rising pressure signals clearing.
How we measure it
Mean sea-level pressure (hPa) for the current hour from Open-Meteo.
Sea-level pressure guide
- > 1030 hPaStrong highSettled, often clear; winter fog possible
- 1020–1030 hPaHighGenerally fair and calm
- 1000–1020 hPaNormalTypical range; watch the trend
- 980–1000 hPaLowUnsettled — cloud, rain, wind likely
- < 980 hPaDeep lowStormy; intense systems and cyclones
Within safe range
Between ~1000 and 1030 hPa with a steady trend, expect unremarkable weather — pressure is doing nothing dramatic.
Beyond the range
A fast fall (>3 hPa in 3 hours) means an active system approaching: strengthening wind and precipitation within hours. Deep lows below 980 hPa power gales and tropical systems. Some people feel pressure swings as headaches or joint aches — real, if individual.
Precautions
- Watch the trend, not the number — falling fast beats 'low' as a warning.
- Rapid fall on the coast or at sea: secure boats, expect wind shifts.
- Mountain users: pressure drops ~1 hPa per 8 m — use trend at a fixed altitude.
- Pair a falling trend with the Wind/Storm and Flood guides for what's coming.