Understanding barometric pressure and terminology
UNDERSTANDING BARROMETRIC PRESSURE AND TERMINOLOGY
Reading in Millibars (mb)
Reading Rising Steady Falling
1032mb and above Settled, Fine Settled, Fine Fine, outlook less settled
1023mb Fine Fine Probably fine with possibility of rain
1015.9mb Probably Fine, Outlook Favourable Probably Fine Changeable, Showers likely
1007.4mb Rain at times, improving Changeable Rain, dry intervals likely
999.0mb Rain Likely Rain Rain
990.0mb and below Heavy Rain Heavy Rain Heavy Rain – Storms
PRESSURE TENDENCY IN STATION REPORTS
Rising or Falling more slowly
Pressure rising (or falling) at a progressively slower rate through the preceding three hours
Rising or Falling slowly
Pressure change of 0.1 to 1.5 mb in the preceding three hours
Rising or Falling
Pressure change of 1.6 to 3.5 mb in the preceding three hours
Rising or Falling quickly
Pressure change of 3.6 to 6.0 mb in the preceding three hours
Rising or Falling very rapidly
Pressure change of more than 6.0 mb in the preceding three hours