How a backyard weather station works

You won't need a meteorologist after you install one of these.

A wet finger will tell you which way the wind blows, but most of us rely on serially inaccurate apps or spray-tanned local meteorologists for detailed readings. The Davis Vantage Pro2 weather station ($650)—a favorite of barometer-tracking fanatics—delivers a personal, hyperlocal forecast from your own backyard. A suite of highly accurate sensors tracks the plunging pressure that precedes a storm, the winds in the buildup, and the downpour that follows. You can also feed your data to Weather Underground, boosting the accuracy of their forecasting algorithm. All that aside, just imagine what it’ll do for your small talk.

Here’s how the instruments make their measurements:

1: Anemometer

The wind vane points into a blowing breeze, indicating its direction. To measure speed, three cups attached to a central rod catch gusts. As the apparatus spins, it rotates a magnet past a sensor, which calculates velocity from 1 mile per hour to more than 200.

Davis Weather station
A station designed for all kinds of weather. Sam Kaplan

2: Rain Collector

Precipitation falls into a bucket, through a debris screen, and onto a 5-inch-long seesaw mechanism. A vessel on either end holds 0.01 inches of water, so as the teeter-totter rocks back and forth, it’s also tallying the rainfall. The spikes keep birds away.

3. Powerplant

Six square inches of solar cells collect energy, while a capacitor and backup battery hold enough voltage to keep the station running for up to a year without sunlight. Onboard processors ready sensor data to broadcast up to 1,000 feet via radio antenna.

4: Thermometer

A radiation shield protects a digital temperature and humidity sensor nestled inside. The white plastic reflects the sun’s rays rather than absorbing them, keeping the sensor accurate within 0.1 degree—from 40 below zero up to 150 degrees Fahrenheit.

5. Mission Control

Every 2.5 seconds, the system sends metrics to a 7-inch-display-equipped control station. Using this data and an onboard barometer, it can generate forecasts for the next 12 to 48 hours. It also stores weather recaps going back years.

This article originally appeared in the Extreme Weather issue of Popular Science under the title, “Storm Brain.”