Weather measurement for pressure

Atmospheric pressure is the force exerted at any given point on the Earth’s surface by the weight of the air above that point - the pressure is lower as you ascend higher into the sky. The air pressure at sea level at a temperature of 59°F (15°C) is equal to one atmosphere (Atm), and this is the baseline reading for determining relative pressure.

Atmospheric pressure is measured by an instrument called a barometer. When the air is dry, cool, and pleasant, the barometer reading rises. In general, a rising barometer means improving weather. In general, a falling barometer means worsening weather. When atmospheric pressure drops suddenly, this usually indicates that a storm is on its way. When atmospheric pressure remains steady, there will likely be no immediate change in the weather.

Hi Ashtonplacecircle,

Thank you for using the Apple Support Communities! Check out this article that list all the data sources used in the Weather app that can help:

Feature availability and data sources in the Weather app

Hope this helps!

Have a great day.

Start here: https://en.wikipedia.org/wiki/Atmospheric_pressure