There are two fundamentally different things a weather app can show you. The first is a model output — a simulation of the atmosphere, run on a grid, then interpolated to your coordinates. The second is an observation — a physical instrument reporting a physical measurement at a specific place and time.
Both are useful. Only one of them can be wrong in a way you'd notice while standing outside.
What makes airport instruments different
- They're calibrated. Maintained to aviation standards, because aircraft make go/no-go decisions on this data.
- They're sited properly. Standard height, open exposure, away from buildings and pavement that would bias readings.
- They're continuous. Hourly at minimum, plus unscheduled special reports the moment conditions change sharply.
- They're public. Collected by NOAA and the National Weather Service, published free, funded by taxes already paid.
A measurement from nine miles away is a real fact about a nearby place. A model estimate for your exact address is a calculated guess about your address. Neither is perfect — but only one of them tells you which it is, and how far away, and how long ago.
What about backyard stations?
Personal weather stations are fun, and there are tens of thousands feeding public networks. They're also wildly inconsistent: a thermometer above a driveway reads hot, one under a tree reads cool, and few are ever recalibrated. For a hobbyist tracking their own yard, that's fine. For deciding whether to fly a drone, shoot a wedding outdoors, or drive across town, calibrated beats convenient.
Distance is information, not a flaw
The right response isn't to hide how far away the sensor is — it's to show it. Knowing the reading came from a station nine miles northwest, six minutes ago, tells you exactly how much to trust it for your street. That's a more honest transaction than a smoothed number presented as if it were measured on your porch.